is_face_alternating

is_face_alternating(face)

Check if the arcs of the bounding the face are alternating. Used e.g. by detecting a Reidemeister 3-face.

Parameters:

face (tuple) – A list of endpoints forming a face boundary in CCW order.

Returns:

True if all positions share the same parity as face[0], else False.

Return type:

bool