Read Signature from NXP NTAG 21x

import nfc
tag = clf.connect(rdwr={'on-connect': None})
uid = tag.uid
sig = tag.transceive("\x3C\x00")
assert len(sig) == 32 or len(sig) == 34
if len(sig) == 34 and nfc.tag.tt2.crca(sig, 32) == sig[32:34]:
    sig = sig[0:32]