def angle_3points(p0, p1, p2):
vec1 = vector(p1, p0)<EOL>vec2 = vector(p2, p0)<EOL>return math.atan2(np.linalg.norm(np.cross(vec1, vec2)),<EOL>np.dot(vec1, vec2))<EOL>
compute the angle in radians between three 3D points

    Calculated as the angle between p1-p0 and p2-p0.

    Args:
        p0, p1, p2:  indexable objects with
        indices 0, 1, 2 corresponding to 3D cartesian coordinates.

    Returns:
        Angle in radians between (p1-p0) and (p2-p0).
        0.0 if p0==p1 or p0==p2.