import { IObservable } from '../internal/Observable';
export declare type ConcatType = {
    <T>(s0: IObservable<T>, s1: IObservable<T>): IObservable<T>;
    <T>(s0: IObservable<T>): {
        (s1: IObservable<T>): IObservable<T>;
    };
};
export declare const concat: ConcatType;