text: Title: Wait for a socket and an event
  Body: Hi,
  
  Is it possible to wait for both a socket and an event? Something like this:
  
  ```python
  s = socket.socket()
  e = gevent.event.Event()
  
  gevent.wait([s, e])
  # Either the socket or the event is ready
  ```
  
  This code is obviously not valid, but I wonder if there's some trick or workaround to make it work.