ex59_zan9.py

class  NameNotFoundError(Exception):
    pass

def print_key(key, **kwargs):
    try:
        print(f'{key} => {kwargs[key]}')
    except KeyError as e:
        raise NameNotFoundError(f'Name {key} not found')


if __name__ == '__main__':

    conn = {
        'host':'localhost',
        'port':1521,
        'service':'oracle'
    }

    try:
        print_key('host', **conn)
        print_key('ip', **conn)
        print_key('service', **conn)
    except NameNotFoundError as e:
        # pass
        print(f'invalid key:{e}')

    print('---')