Pauses the current green thread for *ms* milliseconds::

            p = h.pipe()

            @h.spawn
            def _():
                p.send('1')
                h.sleep(50)
                p.send('2')

            p.recv() # returns '1'
            p.recv() # returns '2' after 50 ms

def sleep(self, ms=1):
        """
        Pauses the current green thread for *ms* milliseconds::

            p = h.pipe()

            @h.spawn
            def _():
                p.send('1')
                h.sleep(50)
                p.send('2')

            p.recv() # returns '1'
            p.recv() # returns '2' after 50 ms
        """
        self.scheduled.add(ms, getcurrent())
        self.loop.switch()