webSocket = slackApi.rtm(rtmStartResponse.url, this);
  }

  // TODO(jwilson): can I read the response body? Do I have to?
  //                the body from slack is a 0-byte-buffer
  @Override public synchronized void onOpen(WebSocket webSocket, Response response) {
    System.out.println("onOpen: " + response);
  }

  // TOOD(jwilson): decode incoming messages and dispatch them somewhere.

            0L -> -1L // No more bytes in this part.
            else -> source.read(sink, limit)
          }
        }

        error("unreachable") // TODO(jwilson): fix intersectWith() to return T.
      }

      override fun timeout(): Timeout = timeout
    }

    /**
     * Returns a value in [0..maxByteCount] with the number of bytes that can be read from [source] in