/**
 * Mask type for unknown type.
 *
 * @param _input The value to check.
 * @returns `true` if the input is unknown type, `false` otherwise.
 */
export declare const isUnknown: (_input: unknown) => _input is unknown;
/**
 * Mask type for unknown type.
 *
 * @param input The input value to mask as unknown type.
 * @returns Unchanged input value as unknown type.
 */
export declare const unknown: (input: unknown) => unknown;