Add format traits for Work and Target

diff --git a/include/u256.rs b/include/u256.rs
index fadb9412..8935c5e0 100644
--- a/include/u256.rs
+++ b/include/u256.rs
@@ -465,6 +465,52 @@ impl fmt::Debug for U256 {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "{:#x}", self) }
 }
 
+impl fmt::Binary for U256 {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.is_zero() {
+            return f.pad_integral(true, "0b", "0");
+        }
+
+        let mut buf = [0u8; 256];
+        let mut i = 256usize;
+        let mut value = *self;
+
+        #[allow(clippy::indexing_slicing)]
+        while value > Self::ZERO {
+            i -= 1;
+            buf[i] = b'0' + (value.low_u64() & 1) as u8;
+            value = value >> 1;
+        }
+
+        let ascii_slice = buf.get(i..).expect("i <= buf.len()");
+        let s = core::str::from_utf8(ascii_slice).expect("binary digits are valid UTF8");
+        f.pad_integral(true, "0b", s)
+    }
+}
+
+impl fmt::Octal for U256 {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.is_zero() {
+            return f.pad_integral(true, "0o", "0");
+        }
+
+        let mut buf = [0u8; 86];
+        let mut i = 86usize;
+        let mut value = *self;
+
+        #[allow(clippy::indexing_slicing)]
+        while value > Self::ZERO {
+            i -= 1;
+            buf[i] = b'0' + (value.low_u64() & 7) as u8;
+            value = value >> 3;
+        }
+
+        let ascii_slice = buf.get(i..).expect("i <= buf.len()");
+        let s = core::str::from_utf8(ascii_slice).expect("octal digits are valid UTF8");
+        f.pad_integral(true, "0o", s)
+    }
+}
+
 /// Splits a 32 byte array into two 16 byte arrays.
 fn split_in_half(a: [u8; 32]) -> ([u8; 16], [u8; 16]) {
     let mut high = [0_u8; 16];
diff --git a/units/src/pow.rs b/units/src/pow.rs
index c34b7b8a..d3521f10 100644
--- a/units/src/pow.rs
+++ b/units/src/pow.rs
@@ -10,6 +10,7 @@ use arbitrary::{Arbitrary, Unstructured};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+use crate::internal_macros::impl_fmt_traits_for_u32_wrapper;
 use crate::parse_int::{self, PrefixedHexError, UnprefixedHexError};
 
 /// Implement traits and methods shared by `Target` and `Work`.
@@ -72,20 +73,6 @@ macro_rules! do_impl {
             }
         }
 
-        impl fmt::LowerHex for $ty {
-            #[inline]
-            fn fmt(&self, f: &mut fmt::Formatter) -> core::fmt::Result {
-                fmt::LowerHex::fmt(&self.0, f)
-            }
-        }
-
-        impl fmt::UpperHex for $ty {
-            #[inline]
-            fn fmt(&self, f: &mut fmt::Formatter) -> core::fmt::Result {
-                fmt::UpperHex::fmt(&self.0, f)
-            }
-        }
-
         impl core::str::FromStr for $ty {
             type Err = $err_ty;
 
@@ -129,6 +116,7 @@ impl Work {
 }
 
 do_impl!(Work, ParseWorkError);
+impl_fmt_traits_for_u32_wrapper!(Work);
 
 impl Add for Work {
     type Output = Self;
@@ -247,6 +235,7 @@ impl Target {
     pub fn to_work(self) -> Work { Work(self.0.inverse()) }
 }
 do_impl!(Target, ParseTargetError);
+impl_fmt_traits_for_u32_wrapper!(Target);
 
 #[rustfmt::skip]                // Keep public re-exports separate.
 #[cfg(feature = "encoding")]
@@ -728,6 +717,34 @@ mod tests {
         check_fmt_30, 0_u32, "{:.1}", "0";
         check_fmt_31, 0_u32, "{:4.1}", "   0";
         check_fmt_32, 0_u32, "{:04.1}", "0000";
+
+        check_fmt_33, 0_u32, "{:b}", "0";
+        check_fmt_34, 0_u32, "{:#b}", "0b0";
+        check_fmt_35, 42_u32, "{:b}", "101010";
+        check_fmt_36, 42_u32, "{:#b}", "0b101010";
+        check_fmt_37, 42_u32, "{:8b}", "  101010";
+        check_fmt_38, 42_u32, "{:08b}", "00101010";
+        check_fmt_39, 42_u32, "{:<8b}", "101010  ";
+        check_fmt_40, 42_u32, "{:>8b}", "  101010";
+        check_fmt_41, 42_u32, "{:^8b}", " 101010 ";
+        check_fmt_42, 42_u32, "{:#10b}", "  0b101010";
+        check_fmt_43, 42_u32, "{:#010b}", "0b00101010";
+        check_fmt_44, 42_u32, "{:.4b}", "101010";
+        check_fmt_45, 42_u32, "{:10.4b}", "    101010";
+
+        check_fmt_46, 0_u32, "{:o}", "0";
+        check_fmt_47, 0_u32, "{:#o}", "0o0";
+        check_fmt_48, 42_u32, "{:o}", "52";
+        check_fmt_49, 42_u32, "{:#o}", "0o52";
+        check_fmt_50, 42_u32, "{:4o}", "  52";
+        check_fmt_51, 42_u32, "{:04o}", "0052";
+        check_fmt_52, 42_u32, "{:<4o}", "52  ";
+        check_fmt_53, 42_u32, "{:>4o}", "  52";
+        check_fmt_54, 42_u32, "{:^4o}", " 52 ";
+        check_fmt_55, 42_u32, "{:#6o}", "  0o52";
+        check_fmt_56, 42_u32, "{:#06o}", "0o0052";
+        check_fmt_57, 42_u32, "{:.4o}", "52";
+        check_fmt_58, 42_u32, "{:6.4o}", "    52";
     }
 
     #[test]