export declare function isDefined<T>(value: T | undefined): value is T;
export declare function isRecord(value: unknown): value is Record<PropertyKey, unknown>;
export declare function isPropertyKey(value: unknown): value is PropertyKey;
export declare function hasProperty<TSource extends Record<PropertyKey, unknown>, TProperty extends PropertyKey, TType extends () => unknown>(value: TSource, key: TProperty, type?: TType): value is TSource & Record<TProperty, ReturnType<TType>>;
export declare function stringHasValue(value: string | undefined): value is string;
export type StringHasValue<T> = string extends T ? true : '' extends T ? false : T extends string ? true : false;