diff --git a/src/codegen.inc.php b/src/codegen.inc.php
index bcbe000..f40ba2a 100644
--- a/src/codegen.inc.php
+++ b/src/codegen.inc.php
@@ -19,6 +19,17 @@ function get_twig(array $inc_path = [])
   return $twig;
 }
 
+function supported_tokens()
+{
+  return [
+    'default',
+    'optional',
+    'virtual',
+    //TODO: anyone uses it?
+    'is_enum_mask', 
+  ];
+}
+
 function _add_twig_support(\Twig\Environment $twig)
 {
   $twig->addTest(new \Twig\TwigTest('instanceof',