code: public function isWhitespace($whitespaces = " \t\n\r\0\x0B")
      {
          if (null === $whitespaces) {
              $whitespaces = " \t\n\r\0\x0B";
          }
  
          if ($this->isArray && !$this->isGivenKind(T_WHITESPACE)) {
              return false;
          }
  
          return '' === trim($this->content, $whitespaces);
      }
docs: Check if token is whitespace.
  
  @param null|string $whitespaces whitespace characters, default is " \t\n\r\0\x0B"
  
  @return bool