def point_positions(point):
    """
    Iterate point positions.

    Parameters
    ----------
    point : tuple
        A tuple made of id, x, y, dx, dy.

    Returns
    -------
    x, y : tuple
        All combinations of a pair (X,Y) where
        X = x/x-dx/x+dx, Y = y/y-dy/y+dy
    """
    x, y = point[1], point[2]
    dx, dy = point[3], point[4]
    for x_position in (x, x - dx, x + dx):
        for y_position in (y, y - dy, y + dy):
            yield x_position, y_position
