export type NotUndefined<T> = T extends undefined ? never : T;
export type Undefinable<T> = T | undefined;
export declare function isNotUndefined<T>(input: Undefinable<T>): input is NotUndefined<T>;
export declare function isUndefined<T>(input: Undefinable<T>): input is undefined;
/**
 *  Return _input_ as `T` if the passed _input_ is not `undefined`.
 *  Otherwise, throw `TypeError` with the passed `msg`.
 */
export declare function expectNotUndefined<T>(input: Undefinable<T>, msg: string): NotUndefined<T>;
/**
 *  Return _input_ as `T` if the passed _input_ is not `undefined`.
 *  Otherwise, throw `TypeError`.
 */
export declare function unwrapUndefinable<T>(input: Undefinable<T>): NotUndefined<T>;