import { Observable } from 'rxjs'; export declare function last(this: Observable, predicate?: null, defaultValue?: D): Observable; export declare function last(this: Observable, predicate: (value: T, index: number, source: Observable) => value is S, defaultValue?: S): Observable; export declare function last(this: Observable, predicate: (value: T, index: number, source: Observable) => boolean, defaultValue?: D): Observable;