FormDiagram.vertex_attribute

FormDiagram.vertex_attribute(key, name, value=None)[source]

Get or set an attribute of a vertex.

Parameters:

  • key (int) – The vertex identifier.

  • name (str) – The name of the attribute

  • value (object, optional) – The value of the attribute.

Returns:

object | None – The value of the attribute, or None when the function is used as a “setter”.

Raises:

KeyError – If the vertex does not exist.