def _a_in_b(first, second):
    """
    Check if interval a is inside interval b.

    Parameters
    ----------
    a : pybedtools.Interval
        First interval.
    b : pybedtools.Interval
        Second interval.

    Returns
    -------
    bool
        True if a is inside b, false otherwise.

    """
    return first.start >= second.start and first.stop <= second.stop
