Added options and tests for exporters.

internal/strings.go

@@ -8,6 +8,14 @@ func PreferFirst(first string, second string) string {
 	return second
 }
 
+// PreferFirstRune returns first non-empty rune
+func PreferFirstRune(first rune, second rune) rune {
+	if first != 0 {
+		return first
+	}
+	return second
+}
+
 // Contains checks whether []string Contains string
 func Contains(s []string, e string) bool {
 	for _, a := range s {