code: def spawn_later(self, ms, f, *a):
          
          self.scheduled.add(ms, f, *a)
docs: Spawns a callable on a new green thread, scheduled for *ms*
          milliseconds in the future::
  
              def echo(pipe, s):
                  pipe.send(s)
  
              p = h.pipe()
              h.spawn_later(50, echo, p, 'hi')
              p.recv() # returns 'hi' after 50ms