code: function concat (a, b, c) {
  		var text = this._register.getItem(c),
  			items = [],
  			i;
  
  		for (i = c - 1; i >= b; i--) {
  			items.push(this._register.getItem(i));
  		}
  
  		this._register.setItem(a, concat_internal(text, items));
  	}
docs: *************************************************************** concat