def cross(vline, hline):
    """Intersction of edges

    Parameters
    ----------
    vline, hline: list or tuple
    (a, b) of vertical edge, horizontal edge
    """
    x = (vline[0] * hline[1] + vline[1]) / (1 - vline[0] * hline[0])
    y = (hline[0] * vline[1] + hline[1]) / (1 - vline[0] * hline[0])

    return (x, y)