python之查询功能

def fetch(a):
    print('这是所要查询的内容')
    backend_data = 'backend %s'% a
    with open('haproxy.conf','r') as f:
        Itag=False
        res=[]
        for i in f:
            if backend_data==i.strip():
                Itag=True
                continue
            if Itag and i.startswith('backend'):
                break
            if Itag:
                print(i,end='')
                res.append(i)
    return res

def add():
    pass
def delete():
    pass
def change():
    pass
if __name__=='__main__':
    msg='''
        1:查询
        2:增加
        3:删除
        4:修改
        5:推出

    '''
    msg_txt={
        '1':fetch,
        '2':add,
        '3':delete,
        '4':change,
        '5':exit
    }
    while True:
        print(msg)
        res=input('请输入选项:').strip()
        if not res:
            continue
        if res==5:
            break
        data=input('用户在此输入需要查询的数据：')
        ret=msg_txt[res](data)
        print(ret)