import type { AnyConstructor } from './AnyConstructor.js';
/**
 * Is the subject a constructor function.
 *
 * @deprecated this is not a failsafe test,
 * it will return true for any function that can be called with `new`.
 *
 * If the subject is an arrow function,
 * it can still return true after compilation.
 *
 * Thus this function is not safe to use.
 */
export declare function isConstructor(subject: unknown): subject is AnyConstructor;
/**
 * instanceof type guard for unknown value.
 */
export declare function isInstanceof<T extends AnyConstructor>(subject: unknown, constructor: T): subject is InstanceType<T>;
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