diff --git a/sot/opcode_translator/executor/variables/base.py b/sot/opcode_translator/executor/variables/base.py
index c672133ff..397c919ef 100644
--- a/sot/opcode_translator/executor/variables/base.py
+++ b/sot/opcode_translator/executor/variables/base.py
@@ -228,6 +228,7 @@ class VariableBase:
     """
 
     tracker: Tracker  # An attribute to store the Tracker object associated with the variable
+    value: Any
     name_generator = NameGenerator(
         "object_"
     )  # A class-level attribute to generate names for new variables
diff --git a/sot/opcode_translator/executor/variables/iter.py b/sot/opcode_translator/executor/variables/iter.py
index 9b1aa1c0d..0dd7c263c 100644
--- a/sot/opcode_translator/executor/variables/iter.py
+++ b/sot/opcode_translator/executor/variables/iter.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, Sized
 
 from ..tracker import ConstTracker, DummyTracker
 from .base import VariableBase
@@ -13,13 +13,18 @@
     from ..tracker import Tracker
 
 
+class SizedVariable(VariableBase, Sized):
+    def __len__(self) -> int:
+        ...
+
+
 class IterVariable(VariableBase):
     """
     This Variable (include subclasses) should be generated only when simulate GET_ITER opcode
     """
 
     def __init__(
-        self, obj: VariableBase, graph: FunctionGraph, tracker: Tracker
+        self, obj: SizedVariable, graph: FunctionGraph, tracker: Tracker
     ):
         super().__init__(graph, tracker)
         self.hold = obj
@@ -94,7 +99,7 @@ def get_wrapped_items(self):
         return self.get_items()
 
     @staticmethod
-    def from_iterator(value, graph: FunctionGraph | None, tracker: Tracker):
+    def from_iterator(value, graph: FunctionGraph, tracker: Tracker):
         # breakpoint()
         if isinstance(
             value,