code: def test_context_exit_reverts_updated_values(self):
      D = ContextVar("D", 1)
      D.value = 2
      with Context(D=3):
          ...
      assert (
          D.value == 2
      ), f"Expected D to be 2, but was {D.value}. Indicates that Context.__exit__ did not restore to the correct value."
  
imports: import unittest
  from PIL import Image
  from tinygrad.helpers import Context, ContextVar, merge_dicts, strip_parens, prod, round_up, fetch, fully_flatten, from_mv, to_mv
  from tinygrad.shape.symbolic import Variable, NumNode
label_desc: Use image node_id 14 for calling the TestContextVars obj's underlying member method code with example usage: obj.test_context_exit_reverts_updated_values() without return types