How to use the pysftp.CnOpts function in pysftp

rsa_key_path = ICPSudo.get_param('saas_server.rsa_key_path', None)
        rsa_key_passphrase=ICPSudo.get_param('saas_server.rsa_key_passphrase')
        sftp_public_key=ICPSudo.get_param('saas_server.sftp_public_key')

        params = {
            "host": server,
            "username": username,
        }
        if rsa_key_path:
            params["private_key"] = self.rsa_key_path
            if rsa_key_passphrase:
                params["private_key_pass"] = rsa_key_passphrase
        else:
            params["password"] = password

        cnopts = pysftp.CnOpts()
        if sftp_public_key:
            key = paramiko.RSAKey(data=base64.b64decode(sftp_public_key))
            cnopts.hostkeys.add(server, 'ssh-rsa', key)
        else:
            cnopts.hostkeys = None

        with pysftp.Connection(**params, cnopts=cnopts) as sftp:

            # set keepalive to prevent socket closed / connection dropped error
            sftp._transport.set_keepalive(30)
            try:
                sftp.chdir(path)
            except IOError:
                # Create directory and subdirs if they do not exist.
                currentDir = ''
                for dirElement in path.split('/'):

makedirs_safe(parse_path(file_out))
    with open(file_out, 'w') as save_file:
      save_file.write(rows_to_csv(rows).read())

  if 'storage' in destination and destination['storage'].get('bucket') and destination['storage'].get('path'):
    # create the bucket
    bucket_create(auth, project.id, destination['storage']['bucket'])

    # put the file
    file_out = destination['storage']['bucket'] + ':' + destination['storage']['path'] + variant
    if project.verbose: print('SAVING', file_out)
    object_put(auth, file_out, rows_to_csv(rows))

  if 'sftp' in destination:
    try:
      cnopts = pysftp.CnOpts()
      cnopts.hostkeys = None

      path_out, file_out = destination['sftp']['file'].rsplit('.', 1)
      file_out = path_out + variant + file_out

      sftp = pysftp.Connection(host=destination['sftp']['host'], username=destination['sftp']['username'], password=destination['sftp']['password'], port=destination['sftp']['port'], cnopts=cnopts)

      if '/' in file_out:
        dir_out, file_out = file_out.rsplit('/', 1)
        sftp.cwd(dir_out)

      sftp.putfo(rows_to_csv(rows), file_out)

    except e:
      print(str(e))
      traceback.print_exc()

def sftp_copy_subject_files(subject, necessary_files, username, domain, local_subjects_dir, remote_subject_dir,
                            password='', overwrite_files=False, print_traceback=True, port=22):
    import pysftp
    local_subject_dir = op.join(local_subjects_dir, subject)
    if password == '':
        password = ask_for_sftp_password(username)
    try:
        cnopts = pysftp.CnOpts()
        cnopts.hostkeys = None
        sftp_con = pysftp.Connection(domain, username=username, password=password, cnopts=cnopts, port=port)
    except:
        try:
            sftp_con = pysftp.Connection(domain, username=username, password=password, port=port)
        except:
            print("Can't connect via sftp!")
            if print_traceback:
                print(traceback.format_exc())
            return False
    with sftp_con as sftp:
        for fol, files in necessary_files.items():
            fol = fol.replace(':', op.sep)
            if not op.isdir(op.join(local_subject_dir, fol)):
                os.makedirs(op.join(local_subject_dir, fol))
            os.chdir(op.join(local_subject_dir, fol))

def get_file_sftp(host, path_to_file, sftp_configuration):
    """
        Copy an existing file from SFTP via sftp://*host*/*path_to_file* link to a home directory.
        The function return the full path to the file that has been downloaded.
    """
    # disable host key checking
    cnopts = pysftp.CnOpts()
    cnopts.hostkeys = None

    # construct SFTP object and get the file on a server
    with pysftp.Connection(host, username = sftp_configuration["user"], password = sftp_configuration["psswd"],
                           cnopts = cnopts) as sftp:
        sftp.get(path_to_file)

    file_location = gc_write_dir + "/" + re.findall("[^/]*$", path_to_file)[0]
    print("File " + path_to_file + " has got successfully.")
    return file_location

def connect(self):
        """ Establish connection with the server """
        
        if (self.connection_flag == False):
            cnopts = pysftp.CnOpts()
            cnopts.hostkeys = None   
            sftp = pysftp.Connection(self.mySFTP_config.URL, username=self.mySFTP_config.USER, 
                                     password=self.mySFTP_config.PASSWORD, cnopts = cnopts)
            
            self.connection_flag = True
            self.sftp = sftp

self.sftp_ask = (
            'Please enter your login details for %s\n' % self.host
                if self.sftp_ask is None else
            self.sftp_ask
        )
        self.sftp_passwd_file = (
            os.path.join('cache', '%s.login' % self.sftp_host)
                if self.sftp_passwd_file is None else
            self.sftp_passwd_file
        )
        if self.sftp_user is None:
            self.ask_passwd()
        while True:

            self.sftp_passwd = self.sftp_passwd or None
            cnopts = pysftp.CnOpts()
            cnopts.hostkeys = None

            with pysftp.Connection(
                host = self.sftp_host,
                username = self.sftp_user,
                password = self.sftp_passwd,
                port = self.sftp_port,
                cnopts = cnopts
            ) as con:

                try:

                    con.get(self.sftp_filename, self.cache_file_name)
                    break

                except IOError:

def create_session(hostname, username, password):
    cnopts = pysftp.CnOpts()
    cnopts.hostkeys = None
    return pysftp.Connection(hostname, username=username, password=password, cnopts=cnopts)