函数是一种对应规则，通过它当给定任何东西（作为参数）时，可以获得另一个东西（该参数的函数值）。
"Sometimes the most dangerous people are the ones who seem the most ordinary."
到达顶峰的唯 一方法是攀登高山，而不是等待电梯。
"To live is the rarest thing in the world. Most people exist, that is all."
The only way to deal with an unfree world is to become so absolutely free that your very existence is an act of rebellion.
