code: public function custom($sessionId, $mediaId, $event)
      {
          $parameters = [
              'query' => [],
              'body' => json_encode(['sessionId' => $sessionId, 'mediaId' => $mediaId, 'event' => $event], JSON_UNESCAPED_UNICODE),
              'headers' => [],
          ];
  
          $result = $this->post('v1/events/custom', $parameters, true);
  
          return $result;
      }
docs: Track a Media custom event.
  
  NOTICE!
  Execution of this call will be delayed until destruct!
  
  @param int    $sessionId The session id to log the event on
  @param int    $mediaId   The ID of the media in the event
  @param string $event     The event