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