How to unwatch/close change stream

Hi

I tried with break…still it is not working…
Because if there is any change, cs keep on watching using for loop

for change in stream:
.
.

I used kind of flag…if flag is stop, break( with in for loop)…else continue…

As for loop keeps on execute on change…flag doesnt play role here…

My requirement is i have multiple collections in mongo db…i can start any collection to watch and stop any collection to stop watching at any time…

Please advise…