Method repack

flow-rs/src/loader/python/envelope.rs:68–73

(&self, msg: PyObject)

    }

    fn repack(&self, msg: PyObject) -> Self {
        let envelope = self.imp.as_ref().expect(ERR_MSG);
        PyEnvelope {
            imp: Some(envelope.repack(msg)),
        }
    }

    #[getter(extra_data)]
    fn get_extra_data(&self) -> Option<PyObject> {