labels(label, [cb])
Returns items tagged with the given label in the InDesign Script Label pane (Window -> Utilities -> Script Label).
Type: function
Parameter(s):
- label {String}:The label identifier. 
- cb {Function} Optional:The callback function to call with each item in the search result. When this function returns false, the loop stops. Passed arguments:item,loopCount.
Returns:
- 
    {Array}:
 Array of concrete page item instances, e.g. text frame or spline item.