Update constant_fold.py

Author: BobTheBuidler

mypyc/irbuild/constant_fold.py

@@ -16,13 +16,15 @@
 from mypy.nodes import (
     BytesExpr,
     ComplexExpr,
+    DictExpr,
     Expression,
     FloatExpr,
     IntExpr,
     MemberExpr,
     NameExpr,
     OpExpr,
     StrExpr,
+    TupleExpr,
     UnaryExpr,
     Var,
 )