def METHOD_NAME(self) -> int:
    if self._root_fingerprint is None:
        # derive m/0' to obtain root_fingerprint
        n = self._derive_with_cache(
            0,
            [0 | paths.HARDENED],
            new_root=lambda: bip32.from_seed(self.seed, self.curve),
        )
        self._root_fingerprint = n.fingerprint()
    return self._root_fingerprint