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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 upsert(self, doc, namespace, timestamp):
 """Update or insert a document into Solr This method should call whatever add/insert/update method exists for the backend engine and add the document in there. The input will always be one mongo document, represented as a Python dictionary. """

        if self.auto_commit_interval is not None:
            self.solr.add([self._clean_doc(doc, namespace, timestamp)],
                          commit=(self.auto_commit_interval == 0),
                          commitWithin=u(self.auto_commit_interval))
        else:
            self.solr.add([self._clean_doc(doc, namespace, timestamp)],
                          commit=False)