type hints: (trivial) add missing "Optional" qualifiers

### electrum/address_synchronizer.py
@@ -82,7 +82,7 @@ class AddressSynchronizer(Logger, EventListener):
     synchronizer: Optional['Synchronizer']
     verifier: Optional['SPV']
 
-    def __init__(self, db: 'WalletDB', config: 'SimpleConfig', *, name: str = None):
+    def __init__(self, db: 'WalletDB', config: 'SimpleConfig', *, name: str | None = None):
         self.db = db
         self.config = config
         self.name = name
@@ -172,7 +172,7 @@ def get_txin_address(self, txin: TxInput) -> Optional[str]:
         return None
 
     @with_lock
-    def get_txin_value(self, txin: TxInput, *, address: str = None) -> Optional[int]:
+    def get_txin_value(self, txin: TxInput, *, address: str | None = None) -> Optional[int]:
         if txin.value_sats() is not None:
             return txin.value_sats()
         prevout_hash = txin.prevout.txid.hex()
@@ -524,7 +524,7 @@ def _get_tx_sort_key(self, tx_hash: str) -> Tuple[int, int]:
         return height, txpos
 
     @classmethod
-    def tx_height_to_sort_height(cls, height: int = None):
+    def tx_height_to_sort_height(cls, height: int | None = None):
         """Return a height-like value to be used for sorting txs."""
         if height is not None:
             if height > 0:
@@ -970,7 +970,7 @@ def get_utxos(
             confirmed_funding_only: bool = False,
             confirmed_spending_only: bool = False,
             nonlocal_only: bool = False,
-            block_height: int = None,
+            block_height: int | None = None,
     ) -> Sequence[PartialTxInput]:
         if block_height is not None:
             # caller wants the UTXOs we had at a given height; check other parameters

### electrum/bip32.py
@@ -429,9 +429,12 @@ def root_fp_and_der_prefix_from_xkey(xkey: str) -> Tuple[Optional[str], Optional
     return root_fingerprint, derivation_prefix
 
 
-def is_xkey_consistent_with_key_origin_info(xkey: str, *,
-                                            derivation_prefix: str = None,
-                                            root_fingerprint: str = None) -> bool:
+def is_xkey_consistent_with_key_origin_info(
+    xkey: str,
+    *,
+    derivation_prefix: str | None = None,
+    root_fingerprint: str | None = None,
+) -> bool:
     bip32node = BIP32Node.from_xkey(xkey)
     int_path = None
     if derivation_prefix is not None:

### electrum/bolt11.py
@@ -118,7 +118,7 @@ def tagged8(char: str, data8: Sequence[int]) -> Sequence[int]:
     return tagged5(char, convertbits(data8, 8, 5))
 
 
-def int_to_data5(val: int, *, bit_len: int = None) -> Sequence[int]:
+def int_to_data5(val: int, *, bit_len: int | None = None) -> Sequence[int]:
     """Represent big-endian number with as many 0-31 values as it takes.
     If `bit_len` is set, use exactly bit_len//5 values (left-padded with zeroes).
     """

### electrum/channel_db.py
@@ -495,7 +495,7 @@ def add_channel_announcements(self, msg_payloads, *, trusted=True):
 
         self.update_counts()
 
-    def add_verified_channel_info(self, msg: dict, *, capacity_sat: int = None) -> None:
+    def add_verified_channel_info(self, msg: dict, *, capacity_sat: int | None = None) -> None:
         try:
             channel_info = ChannelInfo.from_msg(msg)
         except IncompatibleOrInsaneFeatures:
@@ -664,7 +664,7 @@ def _db_save_node_addresses(self, node_addresses: Sequence[LNPeerAddr]):
                 c.execute("INSERT INTO address (node_id, host, port, timestamp) VALUES (?,?,?,?)", (addr.pubkey, addr.host, addr.port, 0))
 
     @classmethod
-    def verify_channel_update(cls, payload, *, start_node: bytes = None) -> None:
+    def verify_channel_update(cls, payload, *, start_node: bytes | None = None) -> None:
         short_channel_id = payload['short_channel_id']
         short_channel_id = ShortChannelID(short_channel_id)
         if constants.net.rev_genesis_bytes() != payload['chain_hash']:
@@ -760,7 +760,7 @@ def _get_channel_update_for_private_channel(
         start_node_id: bytes,
         short_channel_id: ShortChannelID,
         *,
-        now: int = None,  # unix ts
+        now: int | None = None,  # unix ts
     ) -> Optional[dict]:
         if now is None:
             now = int(time.time())
@@ -776,7 +776,7 @@ def add_channel_update_for_private_channel(
         msg_payload: dict,
         start_node_id: bytes,
         *,
-        cache_ttl: int = None,  # seconds
+        cache_ttl: int | None = None,  # seconds
     ) -> bool:
         """Returns True iff the channel update was successfully added and it was different than
         what we had before (if any).
@@ -931,7 +931,7 @@ def get_policy_for_node(
             *,
             my_channels: Dict[ShortChannelID, 'Channel'] = None,
             private_route_edges: Dict[ShortChannelID, 'RouteEdge'] = None,
-            now: int = None,  # unix ts
+            now: int | None = None,  # unix ts
     ) -> Optional['Policy']:
         channel_info = self.get_channel_info(short_channel_id)
         if channel_info is not None:  # publicly announced channel

### electrum/crypto.py
@@ -362,7 +362,7 @@ def chacha20_poly1305_encrypt(
         *,
         key: bytes,
         nonce: bytes,
-        associated_data: bytes = None,
+        associated_data: bytes | None = None,
         data: bytes
 ) -> bytes:
     assert isinstance(key, (bytes, bytearray))
@@ -387,7 +387,7 @@ def chacha20_poly1305_decrypt(
         *,
         key: bytes,
         nonce: bytes,
-        associated_data: bytes = None,
+        associated_data: bytes | None = None,
         data: bytes
 ) -> bytes:
     assert isinstance(key, (bytes, bytearray))

### electrum/exchange_rate.py
@@ -749,14 +749,14 @@ def exchange_rate(self) -> Decimal:
             return Decimal('NaN')
         return self.exchange.get_cached_spot_quote(self.ccy)
 
-    def format_amount(self, btc_balance, *, timestamp: int = None) -> str:
+    def format_amount(self, btc_balance, *, timestamp: int | None = None) -> str:
         if timestamp is None:
             rate = self.exchange_rate()
         else:
             rate = self.timestamp_rate(timestamp)
         return '' if rate.is_nan() else "%s" % self.value_str(btc_balance, rate)
 
-    def format_amount_and_units(self, btc_balance, *, timestamp: int = None) -> str:
+    def format_amount_and_units(self, btc_balance, *, timestamp: int | None = None) -> str:
         if timestamp is None:
             rate = self.exchange_rate()
         else:

### electrum/gui/qml/qebiometrics.py
@@ -117,7 +117,7 @@ def _disable_protected_failed(self):
 
     @pyqtSlot()
     @pyqtSlot(str)
-    def unlock(self, auth_message: str = None):
+    def unlock(self, auth_message: str | None = None):
         """
         Called when the user needs to authenticate.
         Makes the AndroidKeyStore decrypt our encrypted wrap key, we then use the decrypted wrap key
@@ -128,7 +128,7 @@ def unlock(self, auth_message: str = None):
         assert encrypted_wrap_key, "shouldn't unlock if biometric auth is disabled"
         self._start_activity(BiometricAction.DECRYPT, data=encrypted_wrap_key, auth_message=auth_message)
 
-    def _start_activity(self, action: BiometricAction, data: str, auth_message: str = None):
+    def _start_activity(self, action: BiometricAction, data: str, auth_message: str | None = None):
         assert self._current_action is None, f"don't run concurrent activities: {self._current_action=} {action=}"
         self._current_action = action
 

### electrum/gui/qml/qebip39recovery.py
@@ -71,7 +71,7 @@ def state(self, state: State):
 
     @pyqtSlot(str, str)
     @pyqtSlot(str, str, str)
-    def startScan(self, wallet_type: str, seed: str, seed_extra_words: str = None):
+    def startScan(self, wallet_type: str, seed: str, seed_extra_words: str | None = None):
         if not seed or not wallet_type:
             return
 

### electrum/gui/qml/qetxfinalizer.py
@@ -585,7 +585,7 @@ def on_signed_tx(self, save: bool, tx: Transaction):
                 self._logger.error('Could not save tx')
         self.finished.emit(True, saved, tx.is_complete())
 
-    def on_sign_failed(self, msg: str = None):
+    def on_sign_failed(self, msg: str | None = None):
         self._logger.debug('on_sign_failed')
         self.signError.emit(msg)
 

### electrum/gui/qml/qetypes.py
@@ -120,7 +120,7 @@ def __repr__(self):
 
 
 class QEBytes(QObject):
-    def __init__(self, data: bytes = None, *, parent=None):
+    def __init__(self, data: bytes | None = None, *, parent=None):
         super().__init__(parent)
         self.data = data
 

### electrum/gui/qml/qewallet.py
@@ -596,7 +596,7 @@ def on_sign_complete(self, broadcast, cb: Callable[[Transaction], None] = None,
             self.broadcast(tx)
 
     # this assumes a 2fa wallet, but there are no other tc_sign_wrapper hooks, so that's ok
-    def on_sign_failed(self, cb: Callable[[], None] = None, error: str = None):
+    def on_sign_failed(self, cb: Callable[[], None] | None = None, error: str | None = None):
         self.otpFailed.emit('error', error)
         if cb:
             cb()
@@ -658,7 +658,7 @@ def ln_auth_rejected(self):
         self.paymentAuthRejected.emit()
 
     @auth_protect(message=_('Pay lightning invoice?'), reject='ln_auth_rejected')
-    def pay_lightning_invoice(self, invoice: 'Invoice', amount_msat: int = None):
+    def pay_lightning_invoice(self, invoice: 'Invoice', amount_msat: int | None = None):
         # at this point, the user confirmed the payment, potentially with an override amount.
         # we save the invoice with the override amount if there was no amount defined in the invoice.
         # (this is similar to what the desktop client does)

### electrum/gui/qt/__init__.py
@@ -612,7 +612,7 @@ def version_info(cls):
             ret["pyqt.path"] = ", ".join(PyQt6.__path__ or [])
         return ret
 
-    def do_copy(self, text: str, *, title: str = None) -> None:
+    def do_copy(self, text: str, *, title: str | None = None) -> None:
         self.app.clipboard().setText(text)
         message = _("Text copied to Clipboard") if title is None else _("{} copied to Clipboard").format(title)
         # tooltip cannot be displayed immediately when called from a menu; wait 200ms

### electrum/gui/qt/address_list.py
@@ -350,7 +350,7 @@ def create_menu(self, position):
         run_hook('receive_menu', menu, addrs, self.wallet)
         self.open_menu(menu, position)
 
-    def place_text_on_clipboard(self, text: str, *, title: str = None) -> None:
+    def place_text_on_clipboard(self, text: str, *, title: str | None = None) -> None:
         if is_address(text):
             try:
                 self.wallet.check_address_for_corruption(text)

### electrum/gui/qt/main_window.py
@@ -973,7 +973,7 @@ def format_amount(
             add_thousands_sep=add_thousands_sep,
         )
 
-    def format_amount_and_units(self, amount_sat, *, timestamp: int = None) -> str:
+    def format_amount_and_units(self, amount_sat, *, timestamp: int | None = None) -> str:
         """Returns string with both bitcoin and fiat amounts, in desired units.
         E.g. 500_000 -> '0.005 BTC (191.42 EUR)'
         """
@@ -1205,7 +1205,7 @@ def create_receive_tab(self):
         from .receive_tab import ReceiveTab
         return ReceiveTab(self)
 
-    def do_copy(self, text: str, *, title: str = None) -> None:
+    def do_copy(self, text: str, *, title: str | None = None) -> None:
         self.gui_object.do_copy(text, title=title)
 
     def show_tooltip_after_delay(self, message):
@@ -2404,7 +2404,7 @@ def do_process_from_file(self):
         if tx:
             self.show_transaction(tx)
 
-    def do_process_from_txid(self, *, parent: QWidget = None, txid: str = None):
+    def do_process_from_txid(self, *, parent: QWidget = None, txid: str | None = None):
         if parent is None:
             parent = self
         from electrum import transaction

### electrum/gui/qt/my_treeview.py
@@ -481,7 +481,7 @@ def add_copy_menu(self, menu: QMenu, idx) -> QMenu:
                          self.place_text_on_clipboard(text, title=title))
         return cc
 
-    def place_text_on_clipboard(self, text: str, *, title: str = None) -> None:
+    def place_text_on_clipboard(self, text: str, *, title: str | None = None) -> None:
         self.main_window.do_copy(text, title=title)
 
     def showEvent(self, e: 'QShowEvent'):

### electrum/gui/qt/qrreader/qtmultimedia/camera_dialog.py
@@ -87,7 +87,7 @@ def __init__(self, parent: Optional[QWidget], *, config: SimpleConfig):
         self.last_qr_scan_ts: float = 0.0
         self.camera: QCamera = None
         self.media_capture_session: QMediaCaptureSession = None
-        self._error_message: str = None
+        self._error_message: str | None = None
         self._ok_done: bool = False
         self.camera_sc_conn = None
         self.resolution: QSize = None

### electrum/gui/qt/qrreader/qtmultimedia/validator.py
@@ -43,10 +43,10 @@ class QrReaderValidatorResult():
     def __init__(self):
         self.accepted: bool = False
 
-        self.message: str = None
-        self.message_color: QColor = None
+        self.message: str | None = None
+        self.message_color: QColor | None = None
 
-        self.simple_result : str = None
+        self.simple_result : str | None = None
 
         self.result_usable: Dict[QrCodeResult, bool] = {}
         self.result_colors: Dict[QrCodeResult, QColor] = {}

### electrum/gui/qt/util.py
@@ -146,7 +146,7 @@ def setVisible(self, visible):
 
 
 class HelpMixin:
-    def __init__(self, help_text: str, *, help_title: str = None):
+    def __init__(self, help_text: str, *, help_title: str | None = None):
         assert isinstance(self, QWidget), "HelpMixin must be a QWidget instance!"
         self.help_text = help_text
         self._help_title = help_title or _('Help')
@@ -641,7 +641,7 @@ def __init__(self):
         self.setLineWidth(1)
 
 
-def address_field(addresses, *, btn_text: str = None):
+def address_field(addresses, *, btn_text: str | None = None):
     if btn_text is None:
         btn_text = _('Get wallet address')
     hbox = QHBoxLayout()
@@ -1253,8 +1253,8 @@ def getSaveFileName(
         title,
         filename,
         filter="",
-        default_extension: str = None,
-        default_filter: str = None,
+        default_extension: str | None = None,
+        default_filter: str | None = None,
         config: 'SimpleConfig',
 ) -> Optional[str]:
     """Custom wrapper for getSaveFileName that remembers the path selected by the user."""

### electrum/gui/qt/wizard/wallet.py
@@ -145,7 +145,7 @@ def is_single_password(self):
         # not supported on desktop
         return False
 
-    def create_storage(self, single_password: str = None):
+    def create_storage(self, single_password: str | None = None):
         self._logger.info('Creating wallet from wizard data')
         data = self.get_wizard_data()
 
@@ -1019,7 +1019,7 @@ def apply(self):
 
 
 class SeedExtensionEdit(QWidget):
-    def __init__(self, parent, *, message: str = None, warning: str = None, warn_issue4566: bool = False):
+    def __init__(self, parent, *, message: str | None = None, warning: str | None = None, warn_issue4566: bool = False):
         super().__init__(parent)
 
         self.warn_issue4566 = warn_issue4566

### electrum/gui/qt/wizard/wizard.py
@@ -261,7 +261,7 @@ def is_finalized(self, wizard_data: dict) -> bool:
 class WizardComponent(AbstractQWidget):
     updated = pyqtSignal(object)
 
-    def __init__(self, parent: QWidget, wizard: QEAbstractWizard, *, title: str = None, layout: QLayout = None):
+    def __init__(self, parent: QWidget, wizard: QEAbstractWizard, *, title: str | None = None, layout: QLayout | None = None):
         super().__init__(parent)
         self.setLayout(layout if layout else QVBoxLayout(self))
         self.wizard_data = {}

### electrum/hw_wallet/plugin.py
@@ -363,7 +363,7 @@ def trezor_validate_op_return_output_and_get_data(output: TxOutput) -> bytes:
     return script[2:]
 
 
-def validate_op_return_output(output: TxOutput, *, max_size: int = None) -> None:
+def validate_op_return_output(output: TxOutput, *, max_size: int | None = None) -> None:
     script = output.scriptpubkey
     if script[0] != opcodes.OP_RETURN:
         raise UserFacingException(_("Only OP_RETURN scripts are supported."))

### electrum/interface.py
@@ -268,7 +268,7 @@ def default_framer(self):
         assert max_size > 500_000, f"{max_size=} (< 500_000) is too small"
         return NewlineFramer(max_size=max_size)
 
-    async def close(self, *, force_after: int = None):
+    async def close(self, *, force_after: int | None = None):
         """Closes the connection and waits for it to be closed.
         We try to flush buffered data to the wire, which can take some time.
         """
@@ -498,7 +498,7 @@ async def close(self, *args, **kwargs):
 
 class ServerAddr:
 
-    def __init__(self, host: str, port: Union[int, str], *, protocol: str = None):
+    def __init__(self, host: str, port: Union[int, str], *, protocol: str | None = None):
         assert isinstance(host, str), repr(host)
         if protocol is None:
             protocol = 's'
@@ -1130,7 +1130,7 @@ async def request_fee_estimates(self):
             self.network.update_fee_estimates()
             await asyncio.sleep(60)
 
-    async def close(self, *, force_after: int = None):
+    async def close(self, *, force_after: int | None = None):
         """Closes the connection and waits for it to be closed.
         We try to flush buffered data to the wire, which can take some time.
         """

### electrum/keystore.py
@@ -522,7 +522,7 @@ def test_der_suffix_against_pubkey(der_suffix: Sequence[int], pubkey: bytes) ->
 
 class Xpub(MasterPublicKeyMixin):
 
-    def __init__(self, *, derivation_prefix: str = None, root_fingerprint: str = None):
+    def __init__(self, *, derivation_prefix: str | None = None, root_fingerprint: str | None = None):
         MasterPublicKeyMixin.__init__(self)
         self.xpub = None
         self.xpub_receive = None
@@ -616,7 +616,7 @@ def add_key_origin_from_root_node(self, *, derivation_prefix: str, root_node: BI
         self.add_key_origin(derivation_prefix=derivation_prefix,
                             root_fingerprint=root_node.calc_fingerprint_of_this_node().hex().lower())
 
-    def add_key_origin(self, *, derivation_prefix: str = None, root_fingerprint: str = None) -> None:
+    def add_key_origin(self, *, derivation_prefix: str | None = None, root_fingerprint: str | None = None) -> None:
         assert self.xpub
         if not (root_fingerprint is None or (is_hex_str(root_fingerprint) and len(root_fingerprint) == 8)):
             raise Exception("root fp must be 8 hex characters")
@@ -851,7 +851,7 @@ def get_private_key(self, sequence: Sequence[int], password):
         pk = self._get_private_key_from_stretched_exponent(for_change, n, secexp)
         return pk, False
 
-    def _check_seed(self, hex_seed: str, *, secexp: int = None) -> None:
+    def _check_seed(self, hex_seed: str, *, secexp: int | None = None) -> None:
         if secexp is None:
             secexp = self.stretch_key(hex_seed)
         master_private_key = ecc.ECPrivkey.from_secret_scalar(secexp)

### electrum/lnchannel.py
@@ -500,15 +500,15 @@ def get_oldest_unrevoked_ctn(self, subject: HTLCOwner) -> int:
         pass
 
     @abstractmethod
-    def included_htlcs(self, subject: HTLCOwner, direction: Direction, ctn: int = None) -> Sequence[UpdateAddHtlc]:
+    def included_htlcs(self, subject: HTLCOwner, direction: Direction, ctn: int | None = None) -> Sequence[UpdateAddHtlc]:
         pass
 
     @abstractmethod
     def funding_txn_minimum_depth(self) -> int:
         pass
 
     @abstractmethod
-    def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = None) -> int:
+    def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int | None = None) -> int:
         """This balance (in msat) only considers HTLCs that have been settled by ctn.
         It disregards reserve, fees, and pending HTLCs (in both directions).
         """
@@ -517,7 +517,7 @@ def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = Non
     @abstractmethod
     def balance_minus_outgoing_htlcs(self, whose: HTLCOwner, *,
                                      ctx_owner: HTLCOwner = HTLCOwner.LOCAL,
-                                     ctn: int = None) -> int:
+                                     ctn: int | None = None) -> int:
         """This balance (in msat), which includes the value of
         pending outgoing HTLCs, is used in the UI.
         """
@@ -710,10 +710,10 @@ def funding_txn_minimum_depth(self):
     def is_funding_tx_mined(self, funding_height):
         return funding_height.conf > 1
 
-    def balance_minus_outgoing_htlcs(self, whose: HTLCOwner, *, ctx_owner: HTLCOwner = HTLCOwner.LOCAL, ctn: int = None):
+    def balance_minus_outgoing_htlcs(self, whose: HTLCOwner, *, ctx_owner: HTLCOwner = HTLCOwner.LOCAL, ctn: int | None = None):
         return 0
 
-    def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = None) -> int:
+    def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int | None = None) -> int:
         return 0
 
     def is_frozen_for_sending(self) -> bool:
@@ -1240,7 +1240,7 @@ def add_htlc(self, htlc: UpdateAddHtlc) -> UpdateAddHtlc:
         self.logger.info("add_htlc")
         return htlc
 
-    def receive_htlc(self, htlc: UpdateAddHtlc, onion_packet:bytes = None) -> UpdateAddHtlc:
+    def receive_htlc(self, htlc: UpdateAddHtlc, onion_packet: bytes | None = None) -> UpdateAddHtlc:
         """Adds a new REMOTE HTLC to the channel.
         Action must be initiated by REMOTE.
         """
@@ -1528,7 +1528,7 @@ def extract_preimage_from_htlc_txin(self, txin: TxInput, *, is_deeply_mined: boo
                         error_bytes=None,
                         failure_message=failure)
 
-    def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = None) -> int:
+    def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int | None = None) -> int:
         assert type(whose) is HTLCOwner
         initial = self.config[whose].initial_msat
         return self.hm.get_balance_msat(whose=whose,
@@ -1537,7 +1537,7 @@ def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = Non
                                         initial_balance_msat=initial)
 
     def balance_minus_outgoing_htlcs(self, whose: HTLCOwner, *, ctx_owner: HTLCOwner = HTLCOwner.LOCAL,
-                                     ctn: int = None) -> int:
+                                     ctn: int | None = None) -> int:
         assert type(whose) is HTLCOwner
         if ctn is None:
             ctn = self.get_next_ctn(ctx_owner)
@@ -1546,7 +1546,7 @@ def balance_minus_outgoing_htlcs(self, whose: HTLCOwner, *, ctx_owner: HTLCOwner
         balance_in_htlcs = self.balance_tied_up_in_htlcs_by_direction(ctx_owner, ctn=ctn, direction=direction)
         return committed_balance - balance_in_htlcs
 
-    def balance_tied_up_in_htlcs_by_direction(self, ctx_owner: HTLCOwner = LOCAL, *, ctn: int = None,
+    def balance_tied_up_in_htlcs_by_direction(self, ctx_owner: HTLCOwner = LOCAL, *, ctn: int | None = None,
                                               direction: Direction):
         # in msat
         if ctn is None:
@@ -1641,8 +1641,8 @@ def consider_ctx(*, ctx_owner: HTLCOwner, is_htlc_dust: bool) -> int:
         return max_send_msat
 
 
-    def included_htlcs(self, subject: HTLCOwner, direction: Direction, ctn: int = None, *,
-                       feerate: int = None) -> List[UpdateAddHtlc]:
+    def included_htlcs(self, subject: HTLCOwner, direction: Direction, ctn: int | None = None, *,
+                       feerate: int | None = None) -> List[UpdateAddHtlc]:
         """Returns list of non-dust HTLCs for subject's commitment tx at ctn,
         filtered by direction (of HTLCs).
         """

### electrum/lnhtlc.py
@@ -407,7 +407,7 @@ def _is_htlc_irrevocably_removed_yet(
 
     @with_lock
     def htlcs_by_direction(self, subject: HTLCOwner, direction: Direction,
-                           ctn: int = None) -> Dict[int, UpdateAddHtlc]:
+                           ctn: int | None = None) -> Dict[int, UpdateAddHtlc]:
         """Return the dict of received or sent (depending on direction) HTLCs
         in subject's ctx at ctn, keyed by htlc_id.
 
@@ -432,7 +432,7 @@ def htlcs_by_direction(self, subject: HTLCOwner, direction: Direction,
         return d
 
     @with_lock
-    def htlcs(self, subject: HTLCOwner, ctn: int = None) -> Sequence[Tuple[Direction, UpdateAddHtlc]]:
+    def htlcs(self, subject: HTLCOwner, ctn: int | None = None) -> Sequence[Tuple[Direction, UpdateAddHtlc]]:
         """Return the list of HTLCs in subject's ctx at ctn."""
         assert type(subject) is HTLCOwner
         if ctn is None:
@@ -475,7 +475,7 @@ def was_htlc_failed(self, *, htlc_id: int, htlc_proposer: HTLCOwner) -> bool:
 
     @with_lock
     def all_settled_htlcs_ever_by_direction(self, subject: HTLCOwner, direction: Direction,
-                                            ctn: int = None) -> Sequence[UpdateAddHtlc]:
+                                            ctn: int | None = None) -> Sequence[UpdateAddHtlc]:
         """Return the list of all HTLCs that have been ever settled in subject's
         ctx up to ctn, filtered to only "direction".
         """
@@ -492,7 +492,7 @@ def all_settled_htlcs_ever_by_direction(self, subject: HTLCOwner, direction: Dir
         return d
 
     @with_lock
-    def all_settled_htlcs_ever(self, subject: HTLCOwner, ctn: int = None) -> Sequence[Tuple[Direction, UpdateAddHtlc]]:
+    def all_settled_htlcs_ever(self, subject: HTLCOwner, ctn: int | None = None) -> Sequence[Tuple[Direction, UpdateAddHtlc]]:
         """Return the list of all HTLCs that have been ever settled in subject's
         ctx up to ctn.
         """
@@ -510,7 +510,7 @@ def all_htlcs_ever(self) -> Sequence[Tuple[Direction, UpdateAddHtlc]]:
         return sent + received
 
     @with_lock
-    def get_balance_msat(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = None,
+    def get_balance_msat(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int | None = None,
                          initial_balance_msat: int) -> int:
         """Returns the balance of 'whose' in 'ctx' at 'ctn'.
         Only HTLCs that have been settled by that ctn are counted.

### electrum/lnpeer.py
@@ -330,7 +330,7 @@ def on_error(self, payload):
             return
         raise GracefulDisconnect
 
-    def send_warning(self, channel_id: bytes, message: str = None, *, close_connection=False):
+    def send_warning(self, channel_id: bytes, message: str | None = None, *, close_connection=False):
         """Sends a warning and disconnects if close_connection.
 
         Note:
@@ -349,7 +349,7 @@ def send_warning(self, channel_id: bytes, message: str = None, *, close_connecti
         if close_connection:
             raise GracefulDisconnect
 
-    def send_error(self, channel_id: bytes, message: str = None, *, force_close_channel=False):
+    def send_error(self, channel_id: bytes, message: str | None = None, *, force_close_channel=False):
         """Sends an error message and force closes the channel.
 
         Note:
@@ -993,7 +993,7 @@ async def channel_establishment_flow(
             public: bool,
             zeroconf: bool = False,
             temp_channel_id: bytes,
-            opening_fee: int = None,
+            opening_fee: int | None = None,
     ) -> Tuple[Channel, 'PartialTransaction']:
         """Implements the channel opening flow.
 
@@ -2200,7 +2200,7 @@ def _check_unfulfilled_htlc(
         chan: Channel,
         htlc: UpdateAddHtlc,
         processed_onion: ProcessedOnionPacket,
-        outer_onion_payment_secret: bytes = None,  # used to group trampoline htlcs for forwarding
+        outer_onion_payment_secret: bytes | None = None,  # used to group trampoline htlcs for forwarding
     ) -> str:
         """
         Does additional checks on the incoming htlc and return the payment key if the tests pass,

### electrum/lnrouter.py
@@ -447,7 +447,7 @@ def add_edge_to_blacklist(
         self,
         short_channel_id: ShortChannelID,
         *,
-        now: int = None,
+        now: int | None = None,
         duration: int = 3600,  # seconds
     ) -> None:
         if now is None:

### electrum/lnsweep.py
@@ -934,7 +934,7 @@ def sweep_ctx_anchor(*, ctx: Transaction, multisig_key: Keypair) -> Optional[Par
 def sweep_ctx_to_local(
         *, ctx: Transaction, output_idx: int, witness_script: bytes,
         privkey: bytes, is_revocation: bool,
-        to_self_delay: int = None) -> Optional[PartialTxInput]:
+        to_self_delay: int | None = None) -> Optional[PartialTxInput]:
     """Create a txin that sweeps the 'to_local' output of a commitment
     transaction into our wallet.
 
@@ -963,7 +963,7 @@ def sweep_htlctx_output(
         htlctx_witness_script: bytes,
         privkey: bytes,
         is_revocation: bool,
-        to_self_delay: int = None,
+        to_self_delay: int | None = None,
 ) -> Optional[PartialTxInput]:
     """Create a txn that sweeps the output of a first stage htlc tx
     (i.e. sweeps from an HTLC-Timeout or an HTLC-Success tx).

### electrum/lnutil.py
@@ -2052,7 +2052,7 @@ class ReceivedMPPStatus(NamedTuple):
     # payment key of the final mpp set (derived from inner trampoline onion payment secret)
     # to which the separate trampoline sets htlcs get added once they are complete.
     # https://github.com/lightning/bolts/pull/829/commits/bc7a1a0bc97b2293e7f43dd8a06529e5fdcf7cd2
-    parent_set_key: str = None
+    parent_set_key: str | None = None
 
     def get_first_htlc_timestamp(self) -> Optional[int]:
         return min([mpp_htlc.htlc.timestamp for mpp_htlc in self.htlcs], default=None)

### electrum/lnworker.py
@@ -1706,7 +1706,7 @@ def make_local_config_for_new_channel(
         channel_type: ChannelType,
         multisig_funding_keypair: Optional[Keypair],  # if None, will get derived from channel_seed
         peer_features: LnFeatures,
-        channel_seed: bytes = None,
+        channel_seed: bytes | None = None,
     ) -> LocalConfig:
         if channel_seed is None:
             channel_seed = os.urandom(32)
@@ -1840,7 +1840,7 @@ def open_channel(
             funding_sat: int,
             push_amt_sat: int,
             public: bool = False,
-            password: str = None,
+            password: str | None = None,
     ) -> Tuple[Channel, PartialTransaction]:
 
         fut = asyncio.run_coroutine_threadsafe(self.lnpeermgr.add_peer(connect_str), get_asyncio_loop())
@@ -1887,8 +1887,8 @@ def can_pay_invoice(self, invoice: Invoice) -> bool:
     @log_exceptions
     async def pay_invoice(
             self, invoice: Invoice, *,
-            amount_msat: int = None,  # to overwrite amt in invoice
-            attempts: int = None,  # used only in unit tests
+            amount_msat: int | None = None,  # to overwrite amt in invoice
+            attempts: int | None = None,  # used only in unit tests
             full_path: LNPaymentPath = None,
             channels: Optional[Sequence[Channel]] = None,  # my own direct channels
             budget: Optional[PaymentFeeBudget] = None,  # to limit max fee
@@ -1974,12 +1974,12 @@ async def pay_to_node(
             min_final_cltv_delta: int,
             r_tags,
             invoice_features: int,
-            attempts: int = None,
+            attempts: int | None = None,
             full_path: LNPaymentPath = None,
             fwd_trampoline_onion: OnionPacket = None,
             budget: PaymentFeeBudget,
             channels: Optional[Sequence[Channel]] = None,
-            fw_payment_key: str = None,  # for forwarding
+            fw_payment_key: str | None = None,  # for forwarding
     ) -> None:
         """
         Can raise PaymentFailure, ChannelDBNotLoaded,
@@ -2132,7 +2132,7 @@ async def pay_to_route(
             sent_htlc_info: SentHtlcInfo,
             min_final_cltv_delta: int,
             trampoline_onion: Optional[OnionPacket] = None,
-            fw_payment_key: str = None,
+            fw_payment_key: str | None = None,
     ) -> None:
         """Sends a single HTLC."""
         shi = sent_htlc_info
@@ -2300,7 +2300,7 @@ def _decode_channel_update_msg(cls, chan_upd_msg: bytes) -> Optional[Dict[str, A
             except Exception:
                 return None
 
-    def _check_bolt11_invoice(self, bolt11_invoice: str, *, amount_msat: int = None, max_min_final_cltv_delta=NBLOCK_CLTV_DELTA_TOO_FAR_INTO_FUTURE) -> BOLT11Addr:
+    def _check_bolt11_invoice(self, bolt11_invoice: str, *, amount_msat: int | None = None, max_min_final_cltv_delta=NBLOCK_CLTV_DELTA_TOO_FAR_INTO_FUTURE) -> BOLT11Addr:
         """Parses and validates a bolt11 invoice str into a BOLT11Addr.
         Includes pre-payment checks external to the parser.
         """

### electrum/mnemonic.py
@@ -158,7 +158,7 @@ class Mnemonic(Logger):
     # Seed derivation does not follow BIP39
     # Mnemonic phrase uses a hash based checksum, instead of a wordlist-dependent checksum
 
-    def __init__(self, lang: str = None):
+    def __init__(self, lang: str | None = None):
         Logger.__init__(self)
         lang = lang or 'en'
         self.logger.info(f'language {lang}')
@@ -198,7 +198,7 @@ def mnemonic_decode(self, seed: str) -> int:
             i = i*n + k
         return i
 
-    def make_seed(self, *, seed_type: str = None, num_bits: int = None) -> str:
+    def make_seed(self, *, seed_type: str | None = None, num_bits: int | None = None) -> str:
         from .keystore import bip39_is_checksum_valid
         if seed_type is None:
             seed_type = 'segwit'

### electrum/network.py
@@ -185,7 +185,7 @@ def set_defaults(self):
     def serialize_proxy_cfgstr(self):
         return ':'.join([self.mode, self.host, self.port])
 
-    def deserialize_proxy_cfgstr(self, s: Optional[str], user: str = None, password: str = None) -> None:
+    def deserialize_proxy_cfgstr(self, s: str | None, user: str | None = None, password: str | None = None) -> None:
         if s is None or (isinstance(s, str) and s.lower() == 'none'):
             self.set_defaults()
             self.user = user
@@ -1314,9 +1314,9 @@ async def maintain_main_interface():
     @classmethod
     async def async_send_http_on_proxy(
             cls, method: str, url: str, *,
-            params: dict = None,
-            body: bytes = None,
-            json: dict = None,
+            params: dict | None = None,
+            body: bytes | None = None,
+            json: dict | None = None,
             headers=None,
             on_finish=None,
             timeout=None,
@@ -1366,7 +1366,7 @@ async def send_multiple_requests(
             method: str,
             params: Sequence,
             *,
-            timeout: int = None,
+            timeout: int | None = None,
     ):
         if timeout is None:
             timeout = self.get_network_timeout_seconds(NetworkTimeout.Urgent)

### electrum/onion_message.py
@@ -265,7 +265,7 @@ def send_onion_message_to(
         lnwallet: 'LNWallet',
         node_id_or_blinded_path: bytes,
         destination_payload: dict,
-        session_key: bytes = None
+        session_key: bytes | None = None
 ) -> None:
     if session_key is None:
         session_key = os.urandom(32)

### electrum/payment_identifier.py
@@ -370,7 +370,7 @@ def finalize(
         self,
         *,
         amount_sat: int = 0,
-        comment: str = None,
+        comment: str | None = None,
         on_finished: Callable[['PaymentIdentifier'], None] = None,
     ):
         assert self._state == PaymentIdentifierState.LNURLP_FINALIZE
@@ -381,9 +381,9 @@ def finalize(
     async def _do_finalize(
         self,
         *,
-        amount_sat: int = None,
-        comment: str = None,
-        on_finished: Callable[['PaymentIdentifier'], None] = None,
+        amount_sat: int | None = None,
+        comment: str | None = None,
+        on_finished: Callable[['PaymentIdentifier'], None] | None = None,
     ):
         from .invoices import Invoice
         try:
@@ -617,7 +617,7 @@ def invoice_from_payment_identifier(
     pi: 'PaymentIdentifier',
     wallet: 'Abstract_Wallet',
     amount_sat: Union[int, str],
-    message: str = None
+    message: str | None = None
 ) -> Optional[Invoice]:
     assert pi.state in [PaymentIdentifierState.AVAILABLE,]
     assert pi.is_onchain() if amount_sat == '!' else True  # MAX should only be allowed if pi has onchain destination

### electrum/plugin.py
@@ -78,7 +78,7 @@ class Plugins(DaemonThread):
     keyfile_windows = r'HKEY_LOCAL_MACHINE\SOFTWARE\Electrum\PluginsKey'
 
     @profiler
-    def __init__(self, config: SimpleConfig, gui_name: str = None, cmd_only: bool = False):
+    def __init__(self, config: SimpleConfig, gui_name: str | None = None, cmd_only: bool = False):
         self.config = config
         self.cmd_only = cmd_only  # type: bool
         self.internal_plugin_metadata = {}

### electrum/plugins/nwc/nwcserver.py
@@ -380,7 +380,7 @@ async def _handle_single_request(self, event: nEvent) -> None:
         if task:
             await self.taskgroup.spawn(self.run_request_task(task, request_event=event, request_method=method))
 
-    async def run_request_task(self, task: Awaitable, *, request_event: nEvent, request_method: str = None) -> None:
+    async def run_request_task(self, task: Awaitable, *, request_event: nEvent, request_method: str | None = None) -> None:
         """Catches request handling exceptions and send an error response"""
         try:
             await task
@@ -397,7 +397,7 @@ async def send_error(
         error_type: str,
         error_msg: str = "",
         *,
-        error_restype: str = None,
+        error_restype: str | None = None,
     ) -> None:
         """Sends an error as response to the passed nEvent, containing the error type and message"""
         to_pubkey_hex = causing_event.pubkey

### electrum/plugins/psbt_nostr/psbt_nostr.py
@@ -254,7 +254,7 @@ def mark_pending_event_rcvd(self, event_id):
         self.known_events[event_id] = now()
         run_sync_function_on_asyncio_thread(self.pending.set, block=False)
 
-    def prepare_messages(self, tx: Union[Transaction, PartialTransaction], label: str = None) -> List[Tuple[str, dict]]:
+    def prepare_messages(self, tx: Union[Transaction, PartialTransaction], label: str | None = None) -> List[Tuple[str, dict]]:
         messages = []
         for xpub, pubkey in self.cosigner_list:
             if not self.cosigner_can_sign(tx, xpub):
@@ -265,7 +265,7 @@ def prepare_messages(self, tx: Union[Transaction, PartialTransaction], label: st
             messages.append((pubkey, payload))
         return messages
 
-    def send_psbt(self, tx: Union[Transaction, PartialTransaction], label: str):
+    def send_psbt(self, tx: Union[Transaction, PartialTransaction], label: str | None):
         self.do_send(self.prepare_messages(tx, label), tx.txid())
 
     def do_send(self, messages: List[Tuple[str, dict]], txid: Optional[str] = None):
@@ -278,9 +278,9 @@ def add_transaction_to_wallet(
         self,
         tx: Union['Transaction', 'PartialTransaction'],
         *,
-        label: str = None,
-        on_failure: Callable[[str], None] = None,
-        on_success: Callable[[], None] = None
+        label: str | None = None,
+        on_failure: Callable[[str], None] | None = None,
+        on_success: Callable[[], None] | None = None
     ) -> None:
         assert tx.txid(), "Shouldn't allow to save tx without txid"
         try:

### electrum/plugins/psbt_nostr/qml.py
@@ -65,7 +65,7 @@ def canSendPsbt(self, wallet: 'QEWallet', tx: str) -> bool:
 
     @pyqtSlot(QEWallet, str)
     @pyqtSlot(QEWallet, str, str)
-    def sendPsbt(self, wallet: 'QEWallet', tx: str, label: str = None):
+    def sendPsbt(self, wallet: 'QEWallet', tx: str, label: str | None = None):
         cosigner_wallet = self._plugin.cosigner_wallets.get(wallet.wallet)
         if not cosigner_wallet:
             return

### electrum/submarine_swaps.py
@@ -746,7 +746,7 @@ async def hold_invoice_callback(self, payment_hash: bytes) -> None:
         output = self.create_funding_output(swap)
         self.wallet.txbatcher.add_payment_output('swaps', output)
 
-    def create_normal_swap(self, *, lightning_amount_sat: int, payment_hash: bytes, their_pubkey: bytes = None):
+    def create_normal_swap(self, *, lightning_amount_sat: int, payment_hash: bytes, their_pubkey: bytes | None = None):
         """ server method """
         assert lightning_amount_sat
         if payment_hash.hex() in self._swaps:

### electrum/trampoline.py
@@ -195,9 +195,9 @@ def is_legacy_relay(invoice_features, r_tags) -> Tuple[bool, Set[bytes]]:
 def _extend_trampoline_route(
         route: List[TrampolineEdge],
         *,
-        start_node: bytes = None,
+        start_node: bytes | None = None,
         end_node: bytes,
-        fee_info: tuple = None,
+        fee_info: tuple | None = None,
 ):
     """Extends the route and modifies it in place."""
     if start_node is None:

### electrum/transaction.py
@@ -327,9 +327,9 @@ class TxInput:
 
     def __init__(self, *,
                  prevout: TxOutpoint,
-                 script_sig: bytes = None,
+                 script_sig: bytes | None = None,
                  nsequence: int = 0xffffffff - 1,
-                 witness: bytes = None,
+                 witness: bytes | None = None,
                  is_coinbase_output: bool = False):
         self.prevout = prevout
         self.script_sig = script_sig
@@ -435,7 +435,7 @@ def to_json(self):
             d['witness'] = [x.hex() for x in self.witness_elements()]
         return d
 
-    def serialize_to_network(self, *, script_sig: bytes = None) -> bytes:
+    def serialize_to_network(self, *, script_sig: bytes | None = None) -> bytes:
         if script_sig is None:
             script_sig = self.script_sig
         # Prev hash and index
@@ -1045,7 +1045,7 @@ def serialize_preimage(
         txin_index: int,
         *,
         sighash: Optional[int] = None,
-        sighash_cache: SighashCache = None,
+        sighash_cache: SighashCache | None = None,
     ) -> bytes:
         nVersion = int.to_bytes(self.version, length=4, byteorder="little", signed=True)
         nLocktime = int.to_bytes(self.locktime, length=4, byteorder="little", signed=False)
@@ -1144,7 +1144,7 @@ def verify_sig_for_txin(
         txin_index: int,
         pubkey_bytes: bytes,
         sig: bytes,
-        sighash_cache: SighashCache = None,
+        sighash_cache: SighashCache | None = None,
     ) -> bool:
         txin = self.inputs()[txin_index]
         if txin.is_taproot():
@@ -2336,8 +2336,8 @@ def from_io(
             inputs: Sequence[PartialTxInput],
             outputs: Sequence[PartialTxOutput],
             *,
-            locktime: int = None,
-            version: int = None,
+            locktime: int | None = None,
+            version: int | None = None,
             BIP69_sort: bool = True
     ) -> 'PartialTransaction':
         self = cls()

### electrum/wallet.py
@@ -273,8 +273,8 @@ def __init__(
         self,
         *,
         risk_level: TxSighashRiskLevel = TxSighashRiskLevel.SAFE,
-        short_message: str = None,
-        messages: List[str] = None,
+        short_message: str | None = None,
+        messages: List[str] | None = None,
     ):
         self.risk_level = risk_level
         self.short_message = short_message
@@ -748,7 +748,7 @@ def _set_label(self, key: str, value: Optional[str]) -> None:
             else:
                 self._labels[key] = value
 
-    def set_label(self, name: str, text: str = None) -> bool:
+    def set_label(self, name: str, text: str | None = None) -> bool:
         if not name:
             return False
         changed = False
@@ -1984,7 +1984,7 @@ def make_unsigned_transaction(
             outputs: List[PartialTxOutput],
             inputs: Optional[List[PartialTxInput]] = None,
             fee_policy: FeePolicy,
-            change_addr: str = None,
+            change_addr: str | None = None,
             is_sweep: bool = False,  # used by Wallet_2fa subclass
             rbf: bool = True,
             BIP69_sort: Optional[bool] = True,
@@ -2654,7 +2654,7 @@ def _add_input_utxo_info(
             self,
             txin: PartialTxInput,
             *,
-            address: str = None,
+            address: str | None = None,
     ) -> None:
         # - We prefer to include UTXO (full tx), even for segwit inputs (see #6198).
         # - For witness v0 inputs, we include *both* UTXO and WITNESS_UTXO. UTXO is a strict superset,

### tests/lnhelpers.py
@@ -351,11 +351,11 @@ def prepare_invoice(
         *,
         amount_msat=100_000_000,
         include_routing_hints=False,
-        payment_preimage: bytes = None,
-        payment_hash: bytes = None,
+        payment_preimage: bytes | None = None,
+        payment_hash: bytes | None = None,
         invoice_features: LnFeatures = None,
-        min_final_cltv_delta: int = None,
-        expiry: int = None,
+        min_final_cltv_delta: int | None = None,
+        expiry: int | None = None,
 ) -> Tuple[BOLT11Addr, Invoice]:
     amount_btc = amount_msat/Decimal(COIN*1000)
     if payment_preimage is None and not payment_hash:

### tests/test_lnpeer.py
@@ -412,7 +412,7 @@ async def f(
             *,
             ctn_delta: int = 0,
             revnum_delta: int = 0,
-            last_rev_secret: bytes = None,
+            last_rev_secret: bytes | None = None,
         ) -> tuple[Channel, Channel]:
             alice_lnwallet, bob_lnwallet = self.prepare_lnwallets(self.GRAPH_DEFINITIONS['single_chan']).values()
             alice_channel, bob_channel = create_test_channels(alice_lnwallet=alice_lnwallet, bob_lnwallet=bob_lnwallet)

### tests/test_submarine_swaps.py
@@ -57,7 +57,7 @@ class TestSwapClaim(ToyServerTestCase):
     test, and build its claim tx with the same code the server would use.
     """
 
-    def create_config(self, name: str = None) -> SimpleConfig:
+    def create_config(self, name: str | None = None) -> SimpleConfig:
         config = super().create_config(name)
         config.FEE_POLICY_SWAPS = 'feerate:5000'
         return config

### tests/toyserver/toynetwork.py
@@ -33,7 +33,7 @@ def __init__(self, *, config: SimpleConfig):
         self.interface = None  # type: Interface | None
         self.relay_fee = None  # type: int | None  # sat/kbyte, set from the server on connect
 
-    async def connect(self, server: ToyServer, *, client_name: str = None) -> Interface:
+    async def connect(self, server: ToyServer, *, client_name: str | None = None) -> Interface:
         """connect to server, and wait until we have synced its headers"""
         assert self.interface is None, "already connected"
         interface = Interface(network=self, server=ServerAddr(host="127.0.0.1", port=server.server_port, protocol="t"))