Update expression.py

Author: BobTheBuidler

mypyc/irbuild/expression.py

@@ -8,7 +8,7 @@
 
 import math
 from collections.abc import Sequence
-from typing import Callable, Union
+from typing import Callable, Union, cast
 
 from mypy.nodes import (
     ARG_NAMED,
@@ -1027,8 +1027,8 @@ def constant_fold_expr_or_tuple(expr: Expression) -> ConstantValueOrTuple | None
             return value
         if not isinstance(expr, TupleExpr):
             return None
-        folded: ConstantValueTuple = tuple(map(constant_fold_expr_or_tuple, expr.items))
-        return folded if None not in folded else None
+        folded = tuple(map(constant_fold_expr_or_tuple, expr.items))
+        return cast(ConstantValueTuple, folded) if None not in folded else None
 
     result = {}
     for key_expr, value_expr in items: