Patch #1552024: add decorator support to unparse.py demo script.

(backport from rev. 52488)

Demo/parser/unparse.py

@@ -223,6 +223,9 @@ class Unparser:
 
     def _FunctionDef(self, t):
         self.write("\n")
+        for deco in t.decorators:
+            self.fill("@")
+            self.dispatch(deco)
         self.fill("def "+t.name + "(")
         self.dispatch(t.args)
         self.write(")")