new_contents: try:
      import zlib
  except ImportError:
      import zlibd as zlib
  
  PATTERNS = [
      # Packed results produced by CPy's zlib.compress()
      (b'0', b'x\x9c3\x00\x00\x001\x001'),
      (b'a', b'x\x9cK\x04\x00\x00b\x00b'),
      (b'0' * 100, b'x\x9c30\xa0=\x00\x00\xb3q\x12\xc1'),
      (bytes(range(64)), b'x\x9cc`dbfaec\xe7\xe0\xe4\xe2\xe6\xe1\xe5\xe3\x17\x10\x14\x12\x16\x11\x15\x13\x97\x90\x94\x92\x96\x91\x95\x93WPTRVQUS\xd7\xd0\xd4\xd2\xd6\xd1\xd5\xd370426153\xb7\xb0\xb4\xb2\xb6\xb1\xb5\xb3\x07\x00\xaa\xe0\x07\xe1'),
  ]
  
  for unpacked, packed in PATTERNS:
      assert zlib.decompress(packed) == unpacked
      print(unpacked)
  
subject: Add test for zlibd module.