async def METHOD_NAME(message: t.MutableMapping[str, t.Any]) -> None:
    messages.append(message)
    if message["type"] == "http.response.start" or message.get(
        "more_body", False
    ):
        return
    stream = (message.get("body", b"") for message in messages)
    body = self._parse(stream)
    if not (body is None and self._nullable):
        self._validate(body)
    while messages:
        await send(messages.pop(0))