Function start_response

src/werkzeug/test.py:1252–1262

(status, headers, exc_info=None)

    buffer: list[bytes] = []

    def start_response(status, headers, exc_info=None):  # type: ignore
        nonlocal response

        if exc_info:
            try:
                raise exc_info[1].with_traceback(exc_info[2])
            finally:
                exc_info = None

        response = (status, headers)
        return buffer.append

    app_rv = app(environ, start_response)
    close_func = getattr(app_rv, "close", None)