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.