code: function refreshSyncers(keys) {
  	if (typeof keys === 'string') {
  		keys = [keys]
  	}
  	if (!keys) {
  		keys = Object.keys(this._syncers)
  	}
  	return Promise.all(keys.map(key => {
  		return this._syncers[key].refresh()
  	}))
  }
docs: Refresh syncers state
  
  @param {string|string[]} [keys] - Syncers to refresh