/**
  * (PHP 5 &gt;= 5.0.0)<br/>
  * Checks if current position is valid
  * @link http://php.net/manual/en/iterator.valid.php
  * @return boolean The return value will be casted to boolean and then evaluated.
  * Returns true on success or false on failure.
  */
 public function valid()
 {
     return $this->collection->offsetExists($this->current);
 }