Add a notify function to send one notification.

notification_producer/producer_client.py

@@ -73,3 +73,15 @@ class ProducerClient:
             self.writer.close()
             await self.writer.wait_closed()
 
+    async def notify(self, title, message):
+        await self.connect()
+
+        try:
+            await self.send_notification(title, message)
+            await self.send_notification('', '')
+
+        except asyncio.CancelledError:
+            pass
+        finally:
+            self.writer.close()
+            await self.writer.wait_closed()