def METHOD_NAME(COMPRESSION_LEVEL):
    cfg = Config()
    cfg[COMPRESSION_LEVEL] = 2
    assert 2 == cfg[COMPRESSION_LEVEL]
    assert list(iter(cfg))
    assert 1 == len(cfg)
    del cfg[COMPRESSION_LEVEL]
    assert 0 == cfg[COMPRESSION_LEVEL]
    assert not list(iter(cfg))
    assert 0 == len(cfg)