def start(self, initial_delay=<NUM_LIT:0>):
if self.listener is None:<EOL><INDENT>raise exceptions.NoAsyncListenerError<EOL><DEDENT>elif self._enabled:<EOL><INDENT>return<EOL><DEDENT>self._enabled = True<EOL>
Wait for push updates from device.

        Will throw NoAsyncListenerError if no listner has been set.