def edge_overlap(low1, high1, low2, high2):
    """ Returns true if two lines have >0 overlap

    >>> edge_overlap(0, 1, 1, 2)
    False
    >>> edge_overlap(0, 2, 1, 2)
    True
    >>> edge_overlap(1, 2, 1, 2)
    True
    >>> edge_overlap(1, 2, 0, 1)
    False
    >>> edge_overlap(1, 2, 0, 2)
    True
    >>> edge_overlap(0, 1, 0, 1)
    True
    """
    if low1 < low2:
        return low2 < high1
    else:
        return low1 < high2