def _inside(plane, point, axis):
    """Checks whether a given point is on a 2D plane."""
    x, y = axis
    u = plane[0] - point
    v = plane[1] - point

    a = u[x] * v[y]
    b = u[y] * v[x]
    return a >= b
Checks whether a given point is on a 2D plane.
fiftyone/utils/utils3d.py