def is_colinear_xy(a, b, c):
    """Determine if three points are colinear on the XY-plane.

    Parameters
    ----------
    a : tuple, list, Point
        Point 1.
    b : tuple, list, Point
        Point 2.
    c : tuple, list, Point
        Point 3.

    Returns
    -------
    bool
        ``True`` if the points are colinear.
        ``False`` otherwise.

    """
    ab_x = b[0] - a[0]
    ab_y = b[1] - a[1]
    ac_x = c[0] - a[0]
    ac_y = c[1] - a[1]
    return ab_x * ac_y == ab_y * ac_x
