code: def from_xdr(cls, xdr):
          
          xdr_decode = base64.b64decode(xdr)
          op = Xdr.StellarXDRUnpacker(xdr_decode)
          op = op.unpack_Operation()
          return cls.from_xdr_object(op)
docs: 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.