Update python example

examples/monitor_control.py

@@ -131,12 +131,15 @@
 # you can ask to be notified.
 # this represents the complete current state of the driver
 #
-# DriverClient.receive(Callable[list[Monitor], None])
+# DriverClient.receive(Optional[Callable[list[Monitor], None]])
 client.receive(lambda d: print(d))
 # one way to use this might be to auto update your driver instance
 def set_monitors(data):
     client.monitors = data
+# calling it on a new callback will cancel the old one and set the new one
 client.receive(set_monitors)
+# calling it with no args will cancel the current receiver
+client.receive()
 
 # gets latest states from driver
 #