Creates a :class:`ChangeTrust` object from an XDR Operation
        object.

def from_xdr_object(cls, op_xdr_object):
        """Creates a :class:`ChangeTrust` object from an XDR Operation
        object.

        """
        if not op_xdr_object.sourceAccount:
            source = None
        else:
            source = encode_check(
                'account', op_xdr_object.sourceAccount[0].ed25519).decode()

        line = Asset.from_xdr_object(op_xdr_object.body.changeTrustOp.line)
        limit = Operation.from_xdr_amount(
            op_xdr_object.body.changeTrustOp.limit)

        return cls(source=source, asset=line, limit=limit)