'Reflect all :class:`.Table` objects for all current
:class:`.DeferredReflection` subclasses'

@classmethod
def prepare(cls, engine):

    to_map = _DeferredMapperConfig.classes_for_base(cls)
    for thingy in to_map:
        cls._sa_decl_prepare(thingy.local_table, engine)
        thingy.map()
        mapper = thingy.cls.__mapper__
        metadata = mapper.class_.metadata
        for rel in mapper._props.values():
            if (isinstance(rel, properties.RelationshipProperty) and (rel.secondary is not None)):
                if isinstance(rel.secondary, Table):
                    cls._reflect_table(rel.secondary, engine)
                elif isinstance(rel.secondary, _class_resolver):
                    rel.secondary._resolvers += (cls._sa_deferred_table_resolver(engine, metadata),)
