@classmethod<EOL><INDENT>def hydrate(cls, db, limit):<DEDENT>
<EOL>cls_name = limit.pop('<STR_LIT>')<EOL>if cls_name not in cls._registry:<EOL><INDENT>utils.find_entrypoint(None, cls_name)<EOL><DEDENT>cls = cls._registry.get(cls_name)<EOL>return cls(db, **limit) if cls else None<EOL>
Given a limit dict, as generated by dehydrate(), generate an
appropriate instance of Limit (or a subclass).  If the
required limit class cannot be found, returns None.