How to use the pynvim.api.common.decode_if_bytes function in pynvim

def from_session(cls, session):
        """Create a new Nvim instance for a Session instance.

        This method must be called to create the first Nvim instance, since it
        queries Nvim metadata for type information and sets a SessionHook for
        creating specialized objects from Nvim remote handles.
        """
        session.error_wrapper = lambda e: NvimError(decode_if_bytes(e[1]))
        channel_id, metadata = session.request(b'nvim_get_api_info')

        if IS_PYTHON3:
            # decode all metadata strings for python3
            metadata = walk(decode_if_bytes, metadata)

        types = {
            metadata['types']['Buffer']['id']: Buffer,
            metadata['types']['Window']['id']: Window,
            metadata['types']['Tabpage']['id']: Tabpage,
        }

        return cls(session, channel_id, metadata, types)

def _from_nvim(self, obj, decode=None):
        if decode is None:
            decode = self._decode
        if type(obj) is ExtType:
            cls = self.types[obj.code]
            return cls(self, (obj.code, obj.data))
        if decode:
            obj = decode_if_bytes(obj, decode)
        return obj