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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def search(self, start_ts, end_ts):
 """Called to query Mongo for documents in a time range. """

        for meta_collection_name in self._meta_collections():
            meta_coll = self.meta_database[meta_collection_name]
            for ts_ns_doc in meta_coll.find(
                {"_ts": {"$lte": end_ts, "$gte": start_ts}}
            ):
                yield ts_ns_doc