#51 new: custom language

lib/core/extension/locale.dart

@@ -0,0 +1,20 @@
+import 'package:flutter/material.dart';
+
+extension LocaleX on Locale {
+  String get name {
+    if (countryCode == null) {
+      return languageCode;
+    }
+    return '${languageCode}_$countryCode';
+  }
+}
+
+extension String2Locale on String {
+  Locale get toLocale {
+    final parts = split('_');
+    if (parts.length == 1) {
+      return Locale(parts[0]);
+    }
+    return Locale(parts[0], parts[1]);
+  }
+}