A subtype of Label that uses an underlying array to map an integer id to the value associated with that id.
Backed by an array, but allows some ids to have undefined ('None') value (the ids present are tracked by a bitset).
A partially defined flag label backed by a bitset.
A partially defined label containing values of type L.
This label is suitable to keep a 'flag' type label which some ids have and others don't.
A trait to support adding labels to nodes and edges.