code: def check_py(self, version, name, original, loc, tokens):
          
          internal_assert(len(tokens) == 1, "invalid " + name + " tokens", tokens)
          if self.target_info < get_target_info(version):
              raise self.make_err(CoconutTargetError, "found Python " + ".".join(version) + " " + name, original, loc, target=version)
          else:
              return tokens[0]
docs: Check for Python-version-specific syntax.