docstr: Requesting a missing key will still return None, but warn.
code: def test_missing_key_legacy(self):
      """
      Requesting a missing key will still return None, but warn.
      """
      md = metadata("distinfo-pkg")
      with suppress_known_deprecation():
          assert md["does-not-exist"] is None
  
imports: import re
  import textwrap
  import unittest
  import warnings
  import importlib
  import contextlib
  from .None import fixtures
  from importlib.metadata import Distribution, PackageNotFoundError, distribution, entry_points, files, metadata, requires, version
label_desc: Use image node_id 15 for calling the APITests obj's underlying member method code with example usage: obj.test_missing_key_legacy() without return types