code: public function unregister(Listener $register) {
  			$id = $register->id;
  			$success = false;
  			if (isset($this->_byId[$id])) {
  				unset($this->_byId[$id]);
  				$success = true;
  			}
  			foreach ($this->_bySignal as $signal => $reg) {
  				if (isset($reg[$id])) {
  					unset($this->_bySignal[$signal][$id]);
  				}
  			}
  			return $success;
  		}
docs: Clears the hash list of Listener
  @param Listener $register
  @return bool true if removed