code: def test_iter():
      stack = TreeStack(value=5, parent=None, length=1)
      stack = stack.push(3)
      stack = stack.push(1)
  
      stack_list = list(stack)
      assert list(stack) == [1, 3, 5]
  
imports: import pytest
  from stanza.models.constituency.tree_stack import TreeStack
  from stanza.tests import *
label_desc: Use image node_id 2 for calling a global function with example usage: test_iter() without return types