'return a dynamic mapping of (Mapper, DependencyProcessor) to
True or False, indicating if the DependencyProcessor operates
on objects of that Mapper.
The result is stored in the dictionary persistently once
calculated.'

@util.memoized_property
def _mapper_for_dep(self):

    return util.PopulateDict((lambda tup: (tup[0]._props.get(tup[1].key) is tup[1].prop)))
