code: def parse_param_signature(sig):
      
      match = PARAM_SIG_RE.match(sig.strip())
      if not match:
          raise RuntimeError('Parameter signature invalid, got ' + sig)
      groups = match.groups()
      modifiers = groups[0].split()
      typ, name, _, default = groups[-4:]
      return ParamTuple(name=name, typ=typ,
                        default=default, modifiers=modifiers)
docs: Parse a parameter signature of the form: type name (= default)?