code: public function trim($charList = null)
      {
          if (is_null($charList)) {
              $this->text = trim($this->text);
          } else {
              $this->text = trim($this->text, $charList);
          }
  
          return $this;
      }
docs: Strip whitespace (or other characters) from the beginning and end of a string
  
  @param string $charList Optionally, the stripped characters can also be specified using the charlist parameter.
  Simply list all characters that you want to be stripped. With .. you can specify a range of characters.
  
  @return Text