insert_new_leaf

insert_new_leaf(k, target_endpoint, new_node_name=None)

Insert a new degree-1 vertex attached at the given endpoint position.

Parameters:

• k (PlanarDiagram) – Diagram to modify (in place).

• target_endpoint (tuple) – (node, pos) where the new leaf edge attaches.

• new_node_name (str | None) – Optional explicit name; if omitted, a fresh name is created.

Returns:

The name of the newly created vertex.

Return type:

str