A list of dictionaries of the legs that make up the multi-legged asset.
        Format is {'asset_id': XYZ, 'quantity': ABC_Decimal}
        :param legs:
        :return:

def legs(self, legs):
        """
        A list of dictionaries of the legs that make up the multi-legged asset.
        Format is {'asset_id': XYZ, 'quantity': ABC_Decimal}
        :param legs:
        :return:
        """
        if legs is not None:
            if not isinstance(legs, list):
                raise ValueError("Invalid type for asset legs: %s" % type(legs).__name__)
            if not all([isinstance(leg, dict) for leg in legs]):
                raise ValueError("All asset legs must be dictionaries")
            self._legs = legs