code: def identifier(self):
          
          key = self.get_public_key_hex()
          return ensure_bytes(hexlify(hash160(unhexlify(ensure_bytes(key)))))
docs: Get the identifier for this node.
  
          Extended keys can be identified by the Hash160 (RIPEMD160 after SHA256)
          of the public key's `key`. This corresponds exactly to the data used in
          traditional Bitcoin addresses. It is not advised to represent this data
          in base58 format though, as it may be interpreted as an address that
          way (and wallet software is not required to accept payment to the chain
          key itself).