code: def tearDown(self):
      TestContextVars.ctx.__exit__()
  
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 2 for calling the TestContextVars obj's underlying member method code with example usage: obj.tearDown() without return types