export default class Json {
    protected file: object;
    constructor();
    get(key: string): any;
    set(key: string, value: any): this;
    update(key: string, fn: (value: any) => any): this;
    unset(key: string): this;
    fromFile(filePath: string): this;
    fromString(source: string): this;
    toString(): string;
    toFile(filePath: string): void;
}