public function removeListener(
        string $event,
        callable $listener
    )
    {
        if ($this->_events[$event] ?? false) {

            $key = array_search(
                $listener,
                $this->_events[$event],
                true
            );

            if ($key !== false) {

                array_splice(
                    $this->_events[$event],
                    $key,
                    1
                );
            }
        }

        return $this;
    }