code: private function parseArgumentDefs()
      {
          if (! $this->peek(Token::PAREN_L)) {
              return new NodeList([]);
          }
  
          return $this->many(
              Token::PAREN_L,
              function () {
                  return $this->parseInputValueDef();
              },
              Token::PAREN_R
          );
      }
docs: @return InputValueDefinitionNode[]|NodeList
  
  @throws SyntaxError