/**
 * @packageDocumentation
 * @module Boolean
 */
import { OperatorFunction } from 'rxjs';
/**
 * Returns an Observable that emits a boolean value.
 *
 * The source should emit a `string` or `number` that can be checked with the
 * {@link https://en.wikipedia.org/wiki/Luhn_algorithm|Luhn Algorithm} used to validate identification numbers such as
 * bank cards and IMEI numbers.
 *
 * @category Validation
 *
 * @typeParam T `string` or `number` value to do the comparison against
 *
 * @example
 * Returns if the value passes the Luhn check.
 * ```ts
 * const input = ['4485275742308327', '1111222233334444', '111133332224444'];
 * from(input).pipe(luhnCheck()).subscribe();
 *```
 * Output: `[true, true, false]`
 *
 * @returns Observable that emits an boolean if the source value passes the Luhn check
 */
export declare function luhnCheck<T extends string | number>(): OperatorFunction<T, boolean>;