code: def test_nested_context(self):
      with Context(VARIABLE=1):
          with Context(VARIABLE=2):
              with Context(VARIABLE=3):
                  self.assertEqual(VARIABLE.value, 3)
              self.assertEqual(VARIABLE.value, 2)
          self.assertEqual(VARIABLE.value, 1)
      self.assertEqual(VARIABLE.value, 0)
  
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 12 for calling the TestContextVars obj's underlying member method code with example usage: obj.test_nested_context() without return types