Get margin requirements for intrument (futures only)

        :Retruns:
            margin : dict
                margin requirements for instrument
                (all values are ``None`` for non-futures instruments)

def get_margin_requirement(self):
        """ Get margin requirements for intrument (futures only)

        :Retruns:
            margin : dict
                margin requirements for instrument
                (all values are ``None`` for non-futures instruments)
        """
        contract = self.get_contract()

        if contract.m_secType == "FUT":
            return futures.get_ib_futures(contract.m_symbol, contract.m_exchange)

        # else...
        return {
            "exchange": None,
            "symbol": None,
            "description": None,
            "class": None,
            "intraday_initial": None,
            "intraday_maintenance": None,
            "overnight_initial": None,
            "overnight_maintenance": None,
            "currency": None,
        }