How to Ignore specefic users

I know I need to use the --ignore-users option but I am not sure what format to add the user in.
I have tried adding them in the following methods which did not work.
-–ignore-users “user1,user2,user3”
-–ignore-users “user1, user2, user3”
-–ignore-users “user1“,“user2“,“user3”

Or maybe you can possibly also create an option in the script to only sync a specific user, it would be more convenient than ignoring the rest :)

Thanks