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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 _create_query_string(params):
 """ Support Elasticsearch 5.X """

        parameters = params or {}

        for param, value in parameters.items():
            param_value = str(value).lower() if isinstance(value, bool) else value
            parameters[param] = param_value

        return urlencode(parameters)