createWatch
Creates an subscription on unit (store, event or effect).
Arguments
config
(Object): Configurationunit
(Unit): Target unit (store, event of effect) that will be watchedfn
(Function): Function that will be called when unit is triggered. Accepts unit payload as the first argument.scope
(Scope): An optional scope object (forked instance) to restrict watcher calls on particular scope.
Returns
Subscription: Unsubscribe function