Warmup-1 > sleepIn

https://codingbat.com/prob/p187868
The parameter weekday is true if it is a weekday, and the parameter vacation is true if we are on vacation. We sleep in if it is not a weekday or we're on vacation. Return true if we sleep in.

sleepIn(false, false) → true
sleepIn(true, false) → false
sleepIn(false, true) → true

如果参数weekday是true，那么就是工作日，如果参数vacation是true那么就是在度假。如果不是工作日或者我们在度假，那么就睡个懒觉。能睡懒觉的时候返回true