code: public static function dumpAsString($var, $depth = 10, $highlight = false)
      {
          self::$_output = '';
          self::$_objects = [];
          self::$_depth = $depth;
          self::dumpInternal($var, 0);
          if ($highlight) {
              $result = highlight_string("<?php\n" . self::$_output, true);
              self::$_output = preg_replace('/&lt;\\?php<br \\/>/', '', $result, 1);
          }
  
          return self::$_output;
      }
docs: Dumps a variable in terms of a string.
  This method achieves the similar functionality as var_dump and print_r
  but is more robust when handling complex objects such as Yii controllers.
  @param mixed $var variable to be dumped
  @param int $depth maximum depth that the dumper should go into the variable. Defaults to 10.
  @param bool $highlight whether the result should be syntax-highlighted
  @return string the string representation of the variable