code: def test_units(self):
      Image._apply_env_variables({"PILLOW_BLOCKS_MAX": "2K"})
      assert Image.core.get_blocks_max() == 2 * 1024
      Image._apply_env_variables({"PILLOW_BLOCK_SIZE": "2m"})
      assert Image.core.get_block_size() == 2 * 1024 * 1024
  
imports: import sys
  import pytest
  from PIL import Image
  from .helper import is_pypy
label_desc: Use image node_id 2 for calling the TestEnvVars obj's underlying member method code with example usage: obj.test_units() without return types