Python程序中"if...else..."的简写

简写前

a, b = 40, 40
if a-20<=0:
    b = 0
else:
    b = a-20
print(b)  ## 查看结果是否一样

简写后

a, b = 40, 40
b = (a-20<=0 and 0 or a-20)
print(b)  ## 查看结果是否一样