 	
 	func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
 		
-		let childIndex = getChildIndex(indexPath: indexPath)
-		
-		let invalidIndex = (childIndex >= childDelegates.count)
-		
-		if invalidIndex {
+		guard let childIndex = getValidChildIndex(indexPath: indexPath) else {
 			return
 		}
 		

	
	func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
		
		let childIndex = getChildIndex(indexPath: indexPath)
		
		let invalidIndex = (childIndex >= childDelegates.count)
		
		if invalidIndex {
			return false
		}
		

	
	func tableView(tableView: UITableView, canMoveRowAtIndexPath indexPath: NSIndexPath) -> Bool {
		
		guard let childIndex = getValidChildIndex(indexPath: indexPath) else {
			return false
		}
		
