def METHOD_NAME(self, end_time=None):
    # type: (Optional[int]) -> None
    """
    Marks the end time of a span. This method should be called once.
    :param end_time: The end time of the span, in nanoseconds. Defaults to ``now``.
    """
    if end_time is None:
        end_time = time_ns()
    self._ddspan._finish_ns(end_time)