paramiko连接负载均衡器执行命令时出现usage: ca_shell [-b] [-r]

usage: ca_shell [-b] [-r]
-b: send command in batch mode.
-r: command invoked from RPC.

我的代码是(std_in, std_out, std_err) = ssh.exec_command('?')
print(std_out.read().decode('utf-8'))
感觉可能是.exec_command的问题

传两个参数问题?