Sets the monthly billing settings for this client.

def set_monthly_billing(self, currency, client_pays, markup_percentage, monthly_scheme=None):
        """Sets the monthly billing settings for this client."""
        body = {
            "Currency": currency,
            "ClientPays": client_pays,
            "MarkupPercentage": markup_percentage}

        if monthly_scheme is not None:
            body["MonthlyScheme"] = monthly_scheme

        response = self._put(self.uri_for(
            'setmonthlybilling'), json.dumps(body))