A collection type for arbitrary objects, that indexes them based on (a subset of) their properties. Which properties to look for is specified during the initialization of the MultiIndexedCollection; any hashable objects can be stored inside.
removing/updating objects is also supported.
The MultiIndexedCollection will not automatically know when an object is changed, so calling update manually is necessary in that case.
Optionally, custom dictionary-types can be used, which is nice if you have some special requirements for your dictionary types.