Repeated Substring Pattern

Given a string `s`, check if it can be constructed by taking a substring of it and appending multiple copies of the substring together.   **Example 1:** **Input:** s = "abab" **Output:** true **Explanation:** It is the substring "ab" twice. ``` **Example 2:** **Input:** s = "aba" **Output:** false ``` **Example 3:** **Input:** s = "abcabcabcabc" **Output:** true **Explanation:** It is the substring "abc" four times or the substring "abcabc" twice. ```   **Constraints:** - `1 <= s.length <= 104` - `s` consists of lowercase English letters.