code: def tco_return_handle(tokens):
      
      internal_assert(len(tokens) == 2, "invalid tail-call-optimizable return statement tokens", tokens)
      if tokens[1].startswith("()"):
          return "return _coconut_tail_call(" + tokens[0] + ")" + tokens[1][2:]  # tokens[1] contains \n
      else:
          return "return _coconut_tail_call(" + tokens[0] + ", " + tokens[1][1:]
docs: Process tail-call-optimizable return statements.