summary>
<span>Expand source code</span>
</summary>
<pre><code class="python">@abstractmethod
async def async_process(
    self,
    *,
    req: AsyncBoltRequest,
    resp: BoltResponse,
    # As this method is not supposed to be invoked by bolt-python users,
    # the naming conflict with the built-in one affects
    # only the internals of this method
    next: Callable[[], Awaitable[BoltResponse]],
) -&gt; Optional[BoltResponse]:
    &#34;&#34;&#34;Processes a request data before other middleware and lis