How to use the ecdsa.util.randrange function in ecdsa

def get_rpc_credentials(config: SimpleConfig) -> Tuple[str, str]:
    rpc_user = config.get('rpcuser', None)
    rpc_password = config.get('rpcpassword', None)
    if rpc_user is None or rpc_password is None:
        rpc_user = 'user'
        import ecdsa, base64
        bits = 128
        nbytes = bits // 8 + (bits % 8 > 0)
        pw_int = ecdsa.util.randrange(pow(2, bits))
        pw_b64 = base64.b64encode(
            pw_int.to_bytes(nbytes, 'big'), b'-_')
        rpc_password = to_string(pw_b64, 'ascii')
        config.set_key('rpcuser', rpc_user)
        config.set_key('rpcpassword', rpc_password, save=True)
    elif rpc_password == '':
        _logger.warning('RPC authentication is disabled.')
    return rpc_user, rpc_password

def encrypt_message(self, message, pubkey):
        assert_bytes(message)

        pk = ser_to_point(pubkey)
        if not ecdsa.ecdsa.point_is_valid(generator_secp256k1, pk.x(), pk.y()):
            raise Exception('invalid pubkey')

        ephemeral_exponent = number_to_string(ecdsa.util.randrange(pow(2,256)), generator_secp256k1.order())
        ephemeral = EC_KEY(ephemeral_exponent)
        ecdh_key = point_to_ser(pk * ephemeral.privkey.secret_multiplier)
        key = hashlib.sha512(ecdh_key).digest()
        iv, key_e, key_m = key[0:16], key[16:32], key[32:]
        ciphertext = aes_encrypt_with_iv(key_e, iv, message)
        ephemeral_pubkey = bfh(ephemeral.get_public_key(compressed=True))
        encrypted = b'BIE1' + ephemeral_pubkey + ciphertext
        mac = hmac.new(key_m, encrypted, hashlib.sha256).digest()

        return base64.b64encode(encrypted + mac)

random_seed = lambda n: "%032x"%ecdsa.util.randrange( pow(2,n) )
BIP32_PRIME = 0x80000000

def generate_seed():
    return "%032x" % ecdsa.util.randrange(pow(2, 128))    

def generate_secret():
    return ecdsa.util.randrange(SECP256k1.order)

    @classmethod
    def encrypt_message(cls, message, pubkey):

        pk = ser_to_point(pubkey)
        if not ecdsa.ecdsa.point_is_valid(generator_secp256k1, pk.x(), pk.y()):
            raise Exception('invalid pubkey')

        ephemeral_exponent = number_to_string(ecdsa.util.randrange(pow(2, 256)),
                                              generator_secp256k1.order())
        ephemeral = EC_KEY(ephemeral_exponent)
        ecdh_key = point_to_ser(pk * ephemeral.privkey.secret_multiplier)
        key = hashlib.sha512(ecdh_key).digest()
        iv, key_e, key_m = key[0:16], key[16:32], key[32:]
        ciphertext = aes_encrypt_with_iv(key_e, iv, message)
        ephemeral_pubkey = ephemeral.get_public_key(compressed=True).decode('hex')
        encrypted = 'BIE1' + ephemeral_pubkey + ciphertext
        mac = hmac.new(key_m, encrypted, hashlib.sha256).digest()

        return base64.b64encode(encrypted + mac)

def encrypt_message(self, message, pubkey):
        assert_bytes(message)

        pk = ser_to_point(pubkey)
        if not ecdsa.ecdsa.point_is_valid(generator_secp256k1, pk.x(), pk.y()):
            raise Exception('invalid pubkey')

        ephemeral_exponent = number_to_string(ecdsa.util.randrange(pow(2,256)), generator_secp256k1.order())
        ephemeral = EC_KEY(ephemeral_exponent)
        ecdh_key = point_to_ser(pk * ephemeral.privkey.secret_multiplier)
        key = hashlib.sha512(ecdh_key).digest()
        iv, key_e, key_m = key[0:16], key[16:32], key[32:]
        ciphertext = aes_encrypt_with_iv(key_e, iv, message)
        ephemeral_pubkey = bfh(ephemeral.get_public_key(compressed=True))
        encrypted = b'BIE1' + ephemeral_pubkey + ciphertext
        mac = hmac.new(key_m, encrypted, hashlib.sha256).digest()

        return base64.b64encode(encrypted + mac)

def generate(klass, curve=NIST192p, entropy=None, hashfunc=sha1):
        secexp = randrange(curve.order, entropy)
        return klass.from_secret_exponent(secexp, curve, hashfunc)

def encrypt_message(self, message: bytes, magic: bytes = b'BIE1'):
        """
        ECIES encryption/decryption methods; AES-128-CBC with PKCS7 is used as the cipher; hmac-sha256 is used as the mac
        """
        assert_bytes(message)

        randint = ecdsa.util.randrange(CURVE_ORDER)
        ephemeral_exponent = number_to_string(randint, CURVE_ORDER)
        ephemeral = ECPrivkey(ephemeral_exponent)
        ecdh_key = (self * ephemeral.secret_scalar).get_public_key_bytes(compressed=True)
        key = hashlib.sha512(ecdh_key).digest()
        iv, key_e, key_m = key[0:16], key[16:32], key[32:]
        ciphertext = aes_encrypt_with_iv(key_e, iv, message)
        ephemeral_pubkey = ephemeral.get_public_key_bytes(compressed=True)
        encrypted = magic + ephemeral_pubkey + ciphertext
        mac = hmac_oneshot(key_m, encrypted, hashlib.sha256)

        return base64.b64encode(encrypted + mac)

def sign_number(self, number, entropy=None, k=None):
        # returns a pair of numbers
        order = self.privkey.order
        # privkey.sign() may raise RuntimeError in the amazingly unlikely
        # (2**-192) event that r=0 or s=0, because that would leak the key.
        # We could re-try with a different 'k', but we couldn't test that
        # code, so I choose to allow the signature to fail instead.

        # If k is set, it is used directly. In other cases
        # it is generated using entropy function
        if k is not None:
            _k = k
        else:
            _k = randrange(order, entropy)

        assert 1 <= _k < order
        sig = self.privkey.sign(number, _k)
        return sig.r, sig.s