/**
 * @name isBigInt
 * @summary Tests for a `BigInt` object instance.
 * @description
 * Checks to see if the input object is an instance of `BigInt`
 * @example
 * <BR>
 *
 * ```javascript
 * import { isBigInt } from '@polkadot/util';
 *
 * console.log('isBigInt', isBigInt(123_456n)); // => true
 * ```
 */
export declare function isBigInt(value: unknown): value is bigint;