code: function getWhitespace($as_string = true) {
  		$ws = array_keys($this->whitespace);
  		return (($as_string) ? implode('', $ws) : $ws);
  	}
docs: Returns whitespace characters as string/array
  @param bool $as_string Should the result be a string or an array?
  @return string|array
  @see setWhitespace()