public function contains(callable $callback)
    {
        foreach (array_keys($this->storage) as $priority) {
            if (false !== ($index = array_search($callback, $this->storage[$priority], true))) {
                return true;
            }
        }
        return false;
    }
public function contains(callable $callback)
    {
        foreach (array_keys($this->storage) as $priority) {
            if (false !== ($index = array_search($callback, $this->storage[$priority], true))) {
                return true;
            }
        }
        return false;
    }
public function contains ( callable $ callback ) { foreach ( array_keys ( $ this -> storage ) as $ priority ) { if ( false !== ( $ index = array_search ( $ callback , $ this -> storage [ $ priority ] , true ) ) ) { return true ; } } return false ; }
Check if the queue contains a specified callback.
@param  callable $callback
@return boolean
Check if the queue contains a specified callback .