code: public function channel(string $channel_id) : EventChannelInterface
      {
          if (isset($this->channel_adapters[$channel_id])){
              return $this->channel_adapters[$channel_id];
          }
          $adapter = new Stk2kEventChannelAdapter(
              $this->eventstream->channel(
                  $channel_id,
                  function () { return new SimpleEventSource(); },
                  function () { return new WildCardEventEmitter(); }
              )
          );
          $this->channel_adapters[$channel_id] = $adapter;
          return $adapter;
      }
docs: Get channel object
  
  @param string $channel_id
  
  @return EventChannelInterface