docs: public void attach(Pipe pipe)
      {
          //  If we are in the middle of sending a message, we'll add new pipe
          //  into the list of eligible pipes. Otherwise we add it to the list
          //  of active pipes.
          if (more) {
              pipes.add(pipe);
              Collections.swap(pipes, eligible, pipes.size() - 1);
              eligible++;
          }
          else {
              pipes.add(pipe);
              Collections.swap(pipes, active, pipes.size() - 1);
              active++;
              eligible++;
          }
      }