final public function detach($observer)
  {
    $key = array_search($observer, $this->_observers);
    if ($key !== false) {
      unset($this->_observers[$key]);
    }
    return $this;
  }
final public function detach($observer)
  {
    $key = array_search($observer, $this->_observers);
    if ($key !== false) {
      unset($this->_observers[$key]);
    }
    return $this;
  }
final public function detach ( $ observer ) { $ key = array_search ( $ observer , $ this -> _observers ) ; if ( $ key !== false ) { unset ( $ this -> _observers [ $ key ] ) ; } return $ this ; }
Detach observer.

@param callback $observer Observer

@return Event
Detach observer .