def overlap(t1, t2):
    """Checks if one interval contains any overlap with another interval.

    Keyword arguments:
    t1 -- First tuple.
    t2 -- Second tuple.

    Returns:
    Returns -1 if i1 is before i2; 1 if i1 is after i2; and 0 if there is any overlap.
    """
    if t1[1] <= t2[0]:
        return -1
    if t2[1] <= t1[0]:
        return 1
    return 0
