public function add($name, $value = null, $where = '')
    {
        if (!$this->has($name)) {
            $this->set($name, $value, $where);
        }

        return $this;
    }
public function add($name, $value = null, $where = '')
    {
        if (!$this->has($name)) {
            $this->set($name, $value, $where);
        }

        return $this;
    }
public function add ( $ name , $ value = null , $ where = '' ) { if ( ! $ this -> has ( $ name ) ) { $ this -> set ( $ name , $ value , $ where ) ; } return $ this ; }
Adds an item. Does not touch if already exists.
@param int|string   $name  item name
@param array        $value item value
@param string|array $where where to put, see [[setItem()]]
@return $this for chaining
@see setItem()
Adds an item . Does not touch if already exists .