import * as t from 'io-ts';
/**
 * Accept a single value argument
 *
 * @param decoder `io-ts` type that accepts a string
 * @returns `io-ts` decoder that accepts [string] and rejects
 * if provided 0 or more than 1 element
 */
export declare function tupleWithOneElement<T extends t.Type<any, string>>(decoder: T): t.Type<t.TypeOf<T>, [t.OutputOf<T>], unknown>;