def remove(self, document_id, namespace, timestamp):
        """Removes the document from the doc dict.
        """
        try:
            entry = self.doc_dict[document_id]
            entry.doc = None
            entry.update(namespace, timestamp)
        except KeyError:
            raise OperationFailed("Document does not exist: %s" % document_id)
Removes the document from the doc dict.