Palindrome Substring Enumeration Solution

Problem Statement

Given a string `sequence` of length `n`, find and return all unique substrings that are palindromes. The order of the substrings in the output should match their first occurrence in the input string `sequence`. A substring `sub` is considered a palindrome if `sub` equals its reverse (`sub` spelled backwards).

Constraints

• The input string S will not be empty.
• The input string S will not contain any repeated substrings.