python如何跳出while循环

person={'name':'Helen','password':'123'}

while True:

    nm=input('请输入用户名')

    psw=input('请输入密码')

    if nm==person['name'] and psw==person['password']:

        cmd=input('请输入指令：')

        while cmd!='quit':

            cmd = input('请输入指令：')

        break