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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 _client_builder(self):
 """Build Elasticsearch client."""

        client_config = self.app.config.get('SEARCH_CLIENT_CONFIG') or {}
        client_config.setdefault(
            'hosts', self.app.config.get('SEARCH_ELASTIC_HOSTS'))
        client_config.setdefault('connection_class', RequestsHttpConnection)
        return Elasticsearch(**client_config)