@classmethod
def from_seed(cls, seed, testnet=False):
    h = hmac_sha512(b'Bitcoin seed', seed)
    private_key = PrivateKey(secret=big_endian_to_int(h[:32]))
    chain_code = h[32:]
    return cls(private_key=private_key, chain_code=chain_code, testnet=testnet)
@classmethod
def from_seed(cls, seed, testnet=False):
    h = hmac_sha512(b'Bitcoin seed', seed)
    private_key = PrivateKey(secret=big_endian_to_int(h[:32]))
    chain_code = h[32:]
    return cls(private_key=private_key, chain_code=chain_code, testnet=testnet)