def METHOD_NAME(monkeypatch):
    # Asserts that ``None`` values are properly passed through to the
    # UserAgentString class. There are separate tests to assert that
    # ``UserAgentString.to_string()`` can handle ``None`` values.
    monkeypatch.delenv('AWS_EXECUTION_ENV', raising=False)
    monkeypatch.setattr(platform, 'system', lambda: None)
    monkeypatch.setattr(platform, 'release', lambda: None)
    monkeypatch.setattr(platform, 'python_version', lambda: None)
    monkeypatch.setattr(platform, 'python_implementation', lambda: None)
    uas = UserAgentString.from_environment()
    assert uas._execution_env is None
    assert uas._platform_name is None
    assert uas._platform_version is None
    assert uas._python_version is None
    assert uas._python_implementation is None