Add child class for single callable

src/tqdm_publisher/_progress_subscriber.py

@@ -0,0 +1,14 @@
+from ._publisher import TQDMPublisher
+
+
+class TQDMProgressSubscriber(TQDMPublisher):
+    def __init__(self, iterable, *, announcer: "?", request_id: str, message: dict, **tqdm_kwargs):
+        super().__init__(iterable, **tqdm_kwargs)
+
+        def on_progress_update(format_dict) -> None:
+            """
+            Describe what this announcer is all about...
+            """
+            announcer.announce(dict(request_id=request_id, **message))
+
+        self.subscribe(callback=on_progress_update)