def __call__(self, wait_time):
    self._time_elapsed += wait_time
    if (self._time_elapsed >= (self.time_to_wait - self._epsilon)):
        self.callback()
def __call__(self, wait_time):
    self._time_elapsed += wait_time
    if (self._time_elapsed >= (self.time_to_wait - self._epsilon)):
        self.callback()