code: public final boolean register(final Socket socket, final EventsHandler handler, final int events)
      {
          if (socket == null) {
              return false;
          }
          return add(socket, create(socket, handler, events));
      }
docs: Register a Socket for polling on specified events.
  
  @param socket   the registering socket.
  @param handler  the events handler for this socket
  @param events   the events to listen to, as a mask composed by ORing POLLIN, POLLOUT and POLLERR.
  @return true if registered, otherwise false