How to use the pexpect.spawn._spawn function in pexpect

def _spawn(self, command, args=[], preexec_fn=None,
                       dimensions=None):
                self.use_native_pty_fork = False
                pexpect.spawn._spawn(self, command, args, preexec_fn,
                                     dimensions)

}
            for tunnel_type in tunnel_types:
                cmd_type = tunnel_types[tunnel_type]
                if tunnel_type in ssh_tunnels:
                    tunnels = ssh_tunnels[tunnel_type]
                    for tunnel in tunnels:
                        if spawn_local_ssh==False:
                            tunnel = quote(str(tunnel))
                        ssh_options = ssh_options + ' -' + cmd_type + ' ' + str(tunnel)
        cmd = "ssh %s -l %s %s" % (ssh_options, username, server)
        if self.debug_command_string:
            return(cmd)

        # Are we asking for a local ssh command or to spawn one in another session?
        if spawn_local_ssh:
            spawn._spawn(self, cmd)
        else:
            self.sendline(cmd)

        # This does not distinguish between a remote server 'password' prompt
        # and a local ssh 'passphrase' prompt (for unlocking a private key).
        i = self.expect(session_init_regex_array, timeout=login_timeout)

        # First phase
        if i==0:
            # New certificate -- always accept it.
            # This is what you get if SSH does not have the remote host's
            # public key stored in the 'known_hosts' cache.
            self.sendline("yes")
            i = self.expect(session_regex_array)
        if i==2: # password or passphrase
            self.sendline(password)

ssh_options = ssh_options + " -o'NoHostAuthenticationForLocalhost=yes'"
        if self.force_password:
            ssh_options = ssh_options + ' ' + self.SSH_OPTS
        if port is not None:
            ssh_options = ssh_options + ' -p %s'%(str(port))
        if ssh_key is not None:
            try:
                os.path.isfile(ssh_key)
            except:
                raise ExceptionPxssh ('private ssh key does not exist')
            ssh_options = ssh_options + ' -i %s' % (ssh_key)
        cmd = "ssh %s -l %s %s" % (ssh_options, username, server)

        # This does not distinguish between a remote server 'password' prompt
        # and a local ssh 'passphrase' prompt (for unlocking a private key).
        spawn._spawn(self, cmd)
        i = self.expect(["(?i)are you sure you want to continue connecting", original_prompt, "(?i)(?:password)|(?:passphrase for key)", "(?i)permission denied", "(?i)terminal type", TIMEOUT, "(?i)connection closed by remote host"], timeout=login_timeout)

        # First phase
        if i==0:
            # New certificate -- always accept it.
            # This is what you get if SSH does not have the remote host's
            # public key stored in the 'known_hosts' cache.
            self.sendline("yes")
            i = self.expect(["(?i)are you sure you want to continue connecting", original_prompt, "(?i)(?:password)|(?:passphrase for key)", "(?i)permission denied", "(?i)terminal type", TIMEOUT])
        if i==2: # password or passphrase
            self.sendline(password)
            i = self.expect(["(?i)are you sure you want to continue connecting", original_prompt, "(?i)(?:password)|(?:passphrase for key)", "(?i)permission denied", "(?i)terminal type", TIMEOUT])
        if i==4:
            self.sendline(terminal_type)
            i = self.expect(["(?i)are you sure you want to continue connecting", original_prompt, "(?i)(?:password)|(?:passphrase for key)", "(?i)permission denied", "(?i)terminal type", TIMEOUT])

def login(self, server, username, password='', login_timeout=10,
              auto_prompt_reset=True, sync_multiplier=1, port=23):
        args = ['telnet']
        if username is not None:
            args += ['-l', username]
        args += [server, str(port)]
        cmd = ' '.join(args)

        spawn._spawn(self, cmd)  # pylint: disable=protected-access

        try:
            i = self.expect('(?i)(?:password)', timeout=login_timeout)
            if i == 0:
                self.sendline(password)
                i = self.expect([self.original_prompt, 'Login incorrect'], timeout=login_timeout)
            if i:
                raise pxssh.ExceptionPxssh('could not log in: password was incorrect')
        except TIMEOUT:
            if not password:
                # No password promt before TIMEOUT & no password provided
                # so assume everything is okay
                pass
            else:
                raise pxssh.ExceptionPxssh('could not log in: did not see a password prompt')

ssh_options = ssh_options + " -o'NoHostAuthenticationForLocalhost=yes'"
        if self.force_password:
            ssh_options = ssh_options + ' ' + self.SSH_OPTS
        if port is not None:
            ssh_options = ssh_options + ' -p %s'%(str(port))
        if ssh_key is not None:
            try:
                os.path.isfile(ssh_key)
            except:
                raise ExceptionPxssh('private ssh key does not exist')
            ssh_options = ssh_options + ' -i %s' % (ssh_key)
        cmd = "ssh %s -l %s %s" % (ssh_options, username, server)

        # This does not distinguish between a remote server 'password' prompt
        # and a local ssh 'passphrase' prompt (for unlocking a private key).
        spawn._spawn(self, cmd)
        i = self.expect(["(?i)are you sure you want to continue connecting", original_prompt, "(?i)(?:password)|(?:passphrase for key)", "(?i)permission denied", "(?i)terminal type", TIMEOUT, "(?i)connection closed by remote host"], timeout=login_timeout)

        # First phase
        if i==0:
            # New certificate -- always accept it.
            # This is what you get if SSH does not have the remote host's
            # public key stored in the 'known_hosts' cache.
            self.sendline("yes")
            i = self.expect(["(?i)are you sure you want to continue connecting", original_prompt, "(?i)(?:password)|(?:passphrase for key)", "(?i)permission denied", "(?i)terminal type", TIMEOUT])
        if i==2: # password or passphrase
            self.sendline(password)
            i = self.expect(["(?i)are you sure you want to continue connecting", original_prompt, "(?i)(?:password)|(?:passphrase for key)", "(?i)permission denied", "(?i)terminal type", TIMEOUT])
        if i==4:
            self.sendline(terminal_type)
            i = self.expect(["(?i)are you sure you want to continue connecting", original_prompt, "(?i)(?:password)|(?:passphrase for key)", "(?i)permission denied", "(?i)terminal type", TIMEOUT])

def login(self, server, username, password='', original_prompt=r'[#$]', login_timeout=10,
              auto_prompt_reset=True, sync_multiplier=1, port=23):
        cmd = 'telnet -l {} {} {}'.format(username, server, port)

        spawn._spawn(self, cmd)  # pylint: disable=protected-access
        try:
            i = self.expect('(?i)(?:password)', timeout=login_timeout)
            if i == 0:
                self.sendline(password)
                i = self.expect([original_prompt, 'Login incorrect'], timeout=login_timeout)
            if i:
                raise pxssh.ExceptionPxssh('could not log in: password was incorrect')
        except TIMEOUT:
            if not password:
                # There was no password prompt before TIMEOUT, and we didn't
                # have a password to enter. Assume everything is OK.
                pass
            else:
                raise pxssh.ExceptionPxssh('could not log in: did not see a password prompt')

        if not self.sync_original_prompt(sync_multiplier):