ensure_arc

ensure_arc(k, arc_like)

Convert various arc-like inputs into a frozenset of two Endpoints.

Parameters:

• k – A PlanarDiagram containing the arc.

• arc_like – Either a frozenset, set, list, or tuple containing two endpoints (Endpoints or (node, position) tuples).

Returns:

frozenset[Endpoint] – The arc as a frozenset of two validated Endpoints.

Return type:

frozenset[Endpoint]