def covering(self, start, end):
        &#34;&#34;&#34;
        Returns intervals that contain the given range.
        &#34;&#34;&#34;
        # All intervals that start at or before the start and end at or after the end offset
        # we do this by first getting the intervals the start before or at the start
        # then filtering by end
        # NOTE: if the given range is zero length, then if the interval starts before the start
        # it must end at least 1 after the end!
        if start == en