private function exists($offset = null)
    {
        return isset($this->container[$offset !== null ? $offset : $this->position]);
    }
private function exists($offset = null)
    {
        return isset($this->container[$offset !== null ? $offset : $this->position]);
    }
private function exists ( $ offset = null ) { return isset ( $ this -> container [ $ offset !== null ? $ offset : $ this -> position ] ) ; }
Check if element exists. Uses current position if no offset provided

@param int $offset
@return bool
Check if element exists . Uses current position if no offset provided