code: public function emit($event, $parameters)
      {
          if (!isset($this->callbacks[$event])) {
              return;
          }
  
          if (!$this->callbacks[$event][0]) {
              usort($this->callbacks[$event][1], function ($A, $B) {
                  if ($A[0] == $B[0]) {
                      return 0;
                  }
  
                  return ($A[0] > $B[0]) ? 1 : -1;
              });
  
              $this->callbacks[$event][0] = true;
          }
  
          foreach ($this->callbacks[$event][1] as $item) {
              call_user_func_array($item[1], $this->buildParameters($parameters));
          }
      }
docs: Execute each of the subscribed listeners
  
  @param string $event      The name of the event to emit
  @param array  $parameters The arguments