Define __repr__ for WireVectors.

This helps with debugging. Before:

```
>>> import pyrtl
>>> w1 = pyrtl.WireVector(name="w1", bitwidth=1)
>>> w2 = pyrtl.WireVector(name="w2", bitwidth=2)
>>> l = [w1, w2]
>>> l
[<pyrtl.wire.WireVector object at 0x7a3307d84ad0>, <pyrtl.wire.WireVector object at 0x7a3307fc9d10>]
```

After:

```
>>> import pyrtl
>>> w1 = pyrtl.WireVector(name="w1", bitwidth=1)
>>> w2 = pyrtl.WireVector(name="w2", bitwidth=2)
>>> l = [w1, w2]
>>> l
[w1/1W, w2/2W]
```

Author: fdxmw

pyrtl/wire.py

@@ -159,7 +159,10 @@ def __hash__(self):
 
     def __str__(self):
         """A string representation of the wire in 'name/bitwidth code' form."""
-        return ''.join([self.name, '/', str(self.bitwidth), self._code])
+        return f'{self.name}/{self.bitwidth}{self._code}'
+
+    def __repr__(self):
+        return str(self)
 
     def _validate_bitwidth(self, bitwidth):
         if bitwidth is not None:
@@ -934,6 +937,9 @@ def __hash__(self):
     def __str__(self):
         return str(self.wire)
 
+    def __repr__(self):
+        return repr(self.wire)
+
     def __ilshift__(self, other):
         self.wire <<= other
         return self

tests/test_wire.py

@@ -487,6 +487,7 @@ def test_ops(self):
 
                 self.assertEqual(hash(a), hash(wrapped_a))
                 self.assertEqual(str(a), str(wrapped_a))
+                self.assertEqual(repr(a), repr(wrapped_a))
                 self.assertEqual(len(a), len(wrapped_a))
 
                 a_and_b = pyrtl.wire.WireVector(name='a_and_b', bitwidth=4)