bit_nclear
bit_nclear(bs, 2, test_length - 3);
bit_nclear(bs, 0, test_length - 1);
bit_nclear(bs, 0, test_length - 1);
bit_nclear(bs, 0, test_length - 1);
bit_nclear(bs, i, test_length - 1);
bit_nclear(bs, 0, test_length - 1);
bit_nclear(bs, 0, test_length - 1 - i);
bit_nclear(bs, i, i);
bit_nclear(bs, 0, test_length - 1);