pub struct Solution;
剑指 Offer 58 - II. 左旋转字符串 https://leetcode.cn/problems/zuo-xuan-zhuan-zi-fu-chuan-lcof/
TypeId
self
Returns the argument unchanged.
Calls U::from(self).
U::from(self)
That is, this conversion is whatever the implementation of From<T> for U chooses to do.
From<T> for U