How to use the sshtunnel.open_tunnel function in sshtunnel

def check_make_ssh_forward_server_sets_daemon(self, case):
        self.start_echo_and_ssh_server()
        tunnel = sshtunnel.open_tunnel(
            (self.saddr, self.sport),
            ssh_username=SSH_USERNAME,
            ssh_password=SSH_PASSWORD,
            remote_bind_address=(self.eaddr, self.eport),
            logger=self.log,
            ssh_config_file=None,
            allow_agent=False
        )
        try:
            tunnel.daemon_forward_servers = case
            tunnel.start()
            for server in tunnel._server_list:
                self.assertEqual(server.daemon_threads, case)
        finally:
            tunnel.stop()

def test_open_tunnel(self):
        """ Test wrapper method mainly used from CLI """
        server = sshtunnel.open_tunnel(
            (self.saddr, self.sport),
            ssh_username=SSH_USERNAME,
            ssh_password=SSH_PASSWORD,
            remote_bind_address=(self.eaddr, self.eport),
            logger=self.log,
            ssh_config_file=None,
            allow_agent=False
        )
        self.assertEqual(server.ssh_host, self.saddr)
        self.assertEqual(server.ssh_port, self.sport)
        self.assertEqual(server.ssh_username, SSH_USERNAME)
        self.assertEqual(server.ssh_password, SSH_PASSWORD)
        self.assertEqual(server.logger, self.log)
        self.start_echo_and_ssh_server()
        server.start()
        self._check_server_auth()

def capture_stdout_stderr():
    (old_out, old_err) = (sys.stdout, sys.stderr)
    try:
        out = [StringIO(), StringIO()]
        (sys.stdout, sys.stderr) = out
        yield out
    finally:
        (sys.stdout, sys.stderr) = (old_out, old_err)
        out[0] = out[0].getvalue()
        out[1] = out[1].getvalue()


# Ensure that ``ssh_config_file is None`` during tests, exceptions are not
# raised and pkey loading from an SSH agent is disabled
open_tunnel = partial(
    sshtunnel.open_tunnel,
    mute_exceptions=False,
    ssh_config_file=None,
    allow_agent=False,
    skip_tunnel_checkup=True,
)

# CONSTANTS

SSH_USERNAME = get_random_string()
SSH_PASSWORD = get_random_string()
SSH_DSS = b'\x44\x78\xf0\xb9\xa2\x3c\xc5\x18\x20\x09\xff\x75\x5b\xc1\xd2\x6c'
SSH_RSA = b'\x60\x73\x38\x44\xcb\x51\x86\x65\x7f\xde\xda\xa2\x2b\x5a\x57\xd5'
ECDSA = b'\x25\x19\xeb\x55\xe6\xa1\x47\xff\x4f\x38\xd2\x75\x6f\xa5\xd5\x60'
FINGERPRINTS = {
    'ssh-dss': SSH_DSS,
    'ssh-rsa': SSH_RSA,