Implement the export statement

lib/ast.js

@@ -738,6 +738,15 @@ var AST_Import = DEFNODE("Import", "imported_name imported_names module_name", {
     }
 });
 
+var AST_Export = DEFNODE("Export", "exported_definition exported_value is_default", {
+    $documentation: "An `export` statement",
+    $propdoc: {
+        exported_definition: "[AST_Defun|AST_Definitions|AST_DefClass?] An exported definition",
+        exported_value: "[AST_Node?] An exported value",
+        is_default: "[Boolean] Whether this is the default exported value of this module"
+    },
+}, AST_Statement);
+
 var AST_VarDef = DEFNODE("VarDef", "name value", {
     $documentation: "A variable declaration; only appears in a AST_Definitions node",
     $propdoc: {