Dispatch the request to the view function.

        Arguments:
            request_context: The request context, optional as Flask
                omits this argument.

async def dispatch_request(
        self, request_context: Optional[RequestContext]=None,
    ) -> ResponseReturnValue:
        """Dispatch the request to the view function.

        Arguments:
            request_context: The request context, optional as Flask
                omits this argument.
        """
        request_ = (request_context or _request_ctx_stack.top).request
        if request_.routing_exception is not None:
            raise request_.routing_exception

        if request_.method == 'OPTIONS' and request_.url_rule.provide_automatic_options:
            return await self.make_default_options_response()

        handler = self.view_functions[request_.url_rule.endpoint]
        return await handler(**request_.view_args)