/**
 * NOOP chain with *any* type
 */
export declare const any: import("./types").Chain<any, any, never, never>;
/**
 * NOOP chain with *unknown* type
 */
export declare const unknown: import("./types").Chain<unknown, unknown, never, never>;
/**
 * Validates input value not a null or undefined
 */
export declare const required: import("./types").Chain<unknown, unknown, never, string>;
/**
 * Stops chain if value is null or undefined
 */
export declare const optional: import("./types").Chain<unknown, unknown, null | undefined, never>;
/**
 * Stops chain if value is null or undefined and outputs provided *value*
 * @param value
 */
export declare const byDefault: <T>(value: T) => import("./types").Chain<unknown, unknown, T, never>;
/**
 * Validates input value is string
 */
export declare const string: import("./types").Chain<unknown, string, never, string>;
/**
 * Validates input value is number
 */
export declare const number: import("./types").Chain<unknown, number, never, string>;
/**
 * Validates input value is boolean
 */
export declare const boolean: import("./types").Chain<unknown, boolean, never, string>;