make mypy happy

Author: Fidget-Spinner

Tools/cases_generator/tier2_generator.py

@@ -146,8 +146,8 @@ def offset_of(
         assert uop.name.startswith("_GUARD_IP")
         # LPAREN
         next(tkn_iter)
-        inst = next(tkn_iter)
-        self.emit(f" OFFSET_OF_{inst.text};\n")
+        tok = next(tkn_iter)
+        self.emit(f" OFFSET_OF_{tok.text};\n")
         # RPAREN
         next(tkn_iter)
         # SEMI