Append a :class:`CreatePassiveOffer
        <stellar_base.operation.CreatePassiveOffer>` operation to the list of
        operations.

        :param str selling_code: The asset code for the asset the offer creator
            is selling.
        :param selling_issuer: The issuing address for the asset the offer
            creator is selling.
        :type selling_issuer: str, None
        :param str buying_code: The asset code for the asset the offer creator
            is buying.
        :param buying_issuer: The issuing address for the asset the offer
            creator is selling.
        :type buying_issuer: str, None
        :param str amount: Amount of the asset being sold. Set to 0 if you want
            to delete an existing offer.
        :param price: Price of 1 unit of selling in terms of buying. You can pass
            in a number as a string or a dict like `{n: numerator, d: denominator}`
        :type price: str, dict
        :param str source: The source address that is creating a passive offer
            on Stellar's distributed exchange.
        :return: This builder instance.

def append_create_passive_offer_op(self,
                                       selling_code,
                                       selling_issuer,
                                       buying_code,
                                       buying_issuer,
                                       amount,
                                       price,
                                       source=None):
        """Append a :class:`CreatePassiveOffer
        <stellar_base.operation.CreatePassiveOffer>` operation to the list of
        operations.

        :param str selling_code: The asset code for the asset the offer creator
            is selling.
        :param selling_issuer: The issuing address for the asset the offer
            creator is selling.
        :type selling_issuer: str, None
        :param str buying_code: The asset code for the asset the offer creator
            is buying.
        :param buying_issuer: The issuing address for the asset the offer
            creator is selling.
        :type buying_issuer: str, None
        :param str amount: Amount of the asset being sold. Set to 0 if you want
            to delete an existing offer.
        :param price: Price of 1 unit of selling in terms of buying. You can pass
            in a number as a string or a dict like `{n: numerator, d: denominator}`
        :type price: str, dict
        :param str source: The source address that is creating a passive offer
            on Stellar's distributed exchange.
        :return: This builder instance.

        """
        selling = Asset(selling_code, selling_issuer)
        buying = Asset(buying_code, buying_issuer)
        op = operation.CreatePassiveOffer(selling, buying, amount, price,
                                          source)
        return self.append_op(op)