while 判断条件：       #在给定的判断条件为 true 时执行循环体，否则退出循环体

    执行语句

count = 0

while (count < 3):

   print ('The count is:', count)

   count = count + 1

print ("Good bye!")

The count is: 0

The count is: 1

The count is: 2

Good bye!