Fix generation not working for single language

Sources/GenerationLibrary/Generation.swift

@@ -223,17 +223,25 @@ public enum Generation {
         defaultLanguage: String
     ) -> String {
         var result = "func string(for language: String) -> String {\n"
-        for language in getLanguages(dictionary: dictionary) where language != defaultLanguage {
+        let languages = getLanguages(dictionary: dictionary)
+        for language in languages where language != defaultLanguage {
             result += indent("if language.hasPrefix(\"\(language)\") {", by: indentTwo)
             result += indent("\nreturn \(language)", by: indentThree)
             result += indent("\n} else", by: indentTwo)
         }
+        if languages.count <= 1 {
+            result += """
+                return \(defaultLanguage)
+            }
+            """
+        } else {
             result += """
             {
                 return \(defaultLanguage)
             }
             }
             """
+        }
         return result
     }