/** A plain object literal (or `Object.create(null)`): not an array, not a class instance, not a function. */
export declare function isPlainObject(value: unknown): value is Readonly<Record<PropertyKey, unknown>>;
export declare function isNonEmptyString(value: unknown): value is string;
/** Short description of a rejected value for error messages (`null`, `an array`, `builtin 'xstate.assign'`, `number`, ...). */
export declare function describeValue(value: unknown): string;