def at(self, timestamp=None, **kwargs):
        """
        at(timestamp) -> SubRipFile clone

        timestamp argument should be coercible to SubRipFile object.

        A specialization of slice. Return all subtiles visible at the
        timestamp mark.

        Example:
            >>> subs.at((0, 0, 20, 0)).shift(seconds=2)
            >>> subs.at(seconds=20).shift(seconds=2)
        """
        time = timestamp or kwargs
        return self.slice(starts_before=time, ends_after=time)
at(timestamp) -> SubRipFile clone

        timestamp argument should be coercible to SubRipFile object.

        A specialization of slice. Return all subtiles visible at the
        timestamp mark.

        Example:
            >>> subs.at((0, 0, 20, 0)).shift(seconds=2)
            >>> subs.at(seconds=20).shift(seconds=2)