feat(first): Observable<T>.first() can take type guard as the predicate function
feat(first): Observable<T>.first() can take type guard as the predicate function

staltz/RxJSNext,ReactiveX/rxjs,ReactiveX/rxjs,benlesh/RxJS,benlesh/RxJS,adrianomelo/RxJSNext,adrianomelo/RxJSNext,RxJS-CN/RxJS-Docs-CN,ReactiveX/RxJS,kwonoj/RxJS,ReactiveX/rxjs,benlesh/RxJS,martinsik/rxjs,benlesh/RxJS,trxcllnt/RxJS,trxcllnt/RxJS,adrianomelo/RxJS-1,staltz/RxJSNext,SangKa/RxJS-Docs-CN,ReactiveX/RxJS,trxcllnt/RxJS,kwonoj/RxJS,adrianomelo/RxJS-1,kwonoj/RxJS,jayphelps/rxjs,martinsik/rxjs,RxJS-CN/RxJS-Docs-CN,Brocco/RxJS,Brocco/RxJS,SangKa/RxJS-Docs-CN,martinsik/rxjs,ReactiveX/RxJS,kwonoj/RxJS,jayphelps/rxjs,adrianomelo/RxJSNext,staltz/RxJSNext,staltz/RxJSNext,adrianomelo/RxJS-1,trxcllnt/RxJS,SangKa/RxJS-Docs-CN,SangKa/RxJS-Docs-CN,adrianomelo/RxJS-1,IgorMinar/RxJS,martinsik/rxjs,RxJS-CN/RxJS-Docs-CN,RxJS-CN/RxJS-Docs-CN,jayphelps/rxjs,jayphelps/rxjs,Brocco/RxJS,ReactiveX/rxjs,Brocco/RxJS,adrianomelo/RxJSNext,jayphelps/rxjs,IgorMinar/RxJS,ReactiveX/RxJS