# ifelse 判断
_username = ‘dmr‘
_password = ‘123‘
if username == _username and password == _password:
    print(‘welcome user {name} login ....‘.format(name=username))
else:
    print(‘invalid username and password!‘)

# elif
age_of_oldboy = 56
guess_age = int(input(‘guessage;‘))
if guess_age == age_of_oldboy:
    print(‘yes, you get it‘)    
elif guess_age <age_of_oldboy:
    print(‘think bigger‘)
else:
    print(‘think smaller‘)