Manual termination of function

I have a function that should either run a fixed number of cycles or until I tell it to end if I set -1 for the number of cycles.

I could use a script instead and

while true

...

end

and ctrl + c but that is a downright ugly method.

I know there is a more elegant way propably with watching for events but I have no experience with that yet so I don't know where to even start looking there.

What I'm thinking about is that I enter a command and the function finishes the current cycle and then I get the return values.