def _overlap(a_start, a_stop, b_start, b_stop):
    """
    :param a_start:
    :param a_stop:
    :param b_start:
    :param b_stop:
    :return:
    >>> _overlap(1, 5, 1.3, 2)
    True
    >>> _overlap(8, 9, 1.2, 2)
    False
    """
    # thx stack overflow
    overlap = max(0, min(a_stop, b_stop) - max(a_start, b_start))
    return (overlap >0)