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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 fetch_search_document(self, *, index):
 """Fetch the object's document from a search index by id."""

        assert self.pk, "Object must have a primary key before being indexed."
        client = get_client()
        return client.get(index=index, doc_type=self.search_doc_type, id=self.pk)