import { NilRuleChecker } from './nil-rule-checker';
import { GuardResult } from '../../core/guard-result';
/**
 * @class NilIsNull
 */
export declare class NilIsNull extends NilRuleChecker<{
    type: 'isNull';
}> {
    constructor(rule: {
        type: 'isNull';
    }, value: unknown);
    /**
     * @override
     */
    exec(): GuardResult;
    private isNull;
}