code: def _call_matcher(self, _call):
          
          sig = self._spec_signature
          if sig is not None:
              if len(_call) == 2:
                  name = ''
                  args, kwargs = _call
              else:
                  name, args, kwargs = _call
              try:
                  return name, sig.bind(*args, **kwargs)
              except TypeError as e:
                  e.__traceback__ = None
                  return e
          else:
              return _call
docs: Given a call (or simply an (args, kwargs) tuple), return a
          comparison key suitable for matching with other calls.
          This is a best effort method which relies on the spec's signature,
          if available, or falls back on the arguments themselves.