Create the appropriate :class:`Operation` subclass from the XDR
        structure.

        Decode an XDR base64 encoded string and create the appropriate
        :class:`Operation` object.

        :param str xdr: The XDR object to create an :class:`Operation` (or
            subclass) instance from.

def from_xdr(cls, xdr):
        """Create the appropriate :class:`Operation` subclass from the XDR
        structure.

        Decode an XDR base64 encoded string and create the appropriate
        :class:`Operation` object.

        :param str xdr: The XDR object to create an :class:`Operation` (or
            subclass) instance from.

        """
        xdr_decode = base64.b64decode(xdr)
        op = Xdr.StellarXDRUnpacker(xdr_decode)
        op = op.unpack_Operation()
        return cls.from_xdr_object(op)