Return the index of the added element

atom.go

@@ -16,12 +16,14 @@ type Countable interface {
 	*xml.Attr | *Person | *Category | *Link | *ExtensionElement | *Entry
 }
 
-// addToSlice adds a Countable to to a *[]Countable
-func addToSlice[C Countable](slice *[]C, countable C) {
+// addToSlice adds a Countable to to a *[]Countable. It returns an int.
+func addToSlice[C Countable](slice *[]C, countable C) int {
 	if *slice == nil {
 		*slice = make([]C, 0)
 	}
 	*slice = append(*slice, countable)
+
+	return len(*slice) - 1
 }
 
 // deleteFromSlice deletes the Countable with the index from the *[]Countable.