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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 replicate(self, doc_id, source, target, continuous=False):
 """ Starts a replication from the `source` database to the `target` database by writing a document with the id `doc_id` to the "_relicator" database """

        if doc_id in self["_replicator"]:
            return
        data = {
            "_id": doc_id,
            "source": source,
            "target": target,
            "continuous": continuous
        }
        self["_replicator"][doc_id] = data