16 lines
268 B
Python
16 lines
268 B
Python
|
class Bird:
|
||
|
|
pass
|
||
|
|
|
||
|
|
class Duck(Bird): # <1>
|
||
|
|
def quack(self):
|
||
|
|
print('Quack!')
|
||
|
|
|
||
|
|
def alert(birdie): # <2>
|
||
|
|
birdie.quack()
|
||
|
|
|
||
|
|
def alert_duck(birdie: Duck) -> None: # <3>
|
||
|
|
birdie.quack()
|
||
|
|
|
||
|
|
def alert_bird(birdie: Bird) -> None: # <4>
|
||
|
|
birdie.quack()
|