code: function putItem(value) {
    return new Promise((resolve, reject) => {
      return instance.pkgs.then(db => {
        const obj = db.transaction(db.name, 'readwrite')
          .objectStore(db.name);
        const req = obj.put(value);
        req.onerror = event => reject(event);
        req.onsuccess = () => resolve();
      });
    });
  }
docs: Put data object in the store
  @param {string} value - value to store