/**
 * Ensures that a value is a thunk. If it is already a thunk, it is returned as
 * is. If it is not a thunk, it is converted to a thunk.
 *
 * @typeParam A - Value returned by the thunk.
 *
 * @param a - Value to ensure is a thunk.
 *
 * @returns `a` as a a thunk.
 */
export declare const castThunk: <A>(a: A | (() => A)) => (() => A);