refactor: Address comments and add documentation
refactor: Address comments and add documentation

- Also removes unnecessary runtime type check, as we check that prior to ever making this internal call.

martinsik/rxjs,martinsik/rxjs,ReactiveX/rxjs,ReactiveX/RxJS,ReactiveX/RxJS,martinsik/rxjs,ReactiveX/RxJS,benlesh/RxJS,benlesh/RxJS,martinsik/rxjs,ReactiveX/rxjs,benlesh/RxJS,ReactiveX/rxjs,benlesh/RxJS,ReactiveX/RxJS,ReactiveX/rxjs