GraphQL\Language\Lexer::advance PHP Method

    public function advance()
    {
        $token = $this->lastToken = $this->token;
        if ($token->kind !== Token::EOF) {
            do {
                $token = $token->next = $this->readToken($token);
            } while ($token->kind === Token::COMMENT);
            $this->token = $token;
        }
        return $token;
    }

 /**
  * @param string $body
  * @return Token
  */
 private function lexOne($body)
 {
     $lexer = new Lexer(new Source($body));
     return $lexer->advance();
 }