 self._by_end.irange(minimum=(0, offset, 0), maximum=(sys.maxsize, offset, sys.maxsize))

    def at(self, start, end):
        &#34;&#34;&#34;
        Returns an iterable of tuples where start==start and end==end
        &#34;&#34;&#34;
        for intvl in self._by_start.irange(
            minimum=(start, 0, 0), maximum=(start, sys.maxsize, sys.maxsize)
        ):
            if intvl[1] == end:
                yield intvl

    def within(self, start, end):
        &#34;&#34;&#34;
        Returns interva