Non-negative integer solution的用法和樣例：
例句
- You must specify a non-negative integer.
必須指定非負整數。 - The resulting value must be a nonnegative integer less than the sequence's length, and the sequence is asked to assign the assigned object to its item with that index.
最后的值必須是一個(gè)小于該序列長(cháng)度的非負整數，然后該序列就被請求將被賦對象賦值給它帶那個(gè)指標的項。
