Longest Palindromic Substring

Return the longest contiguous substring of text that reads identically forward and backward. If several have maximum length, return the one with the smallest starting index in text. Empty input returns ''. Compare characters case-sensitively. At most 300 characters. Examples (JSON; null means Python None): Input: {"text": "babad"} Output: "bab" Input: {"text": "cbbd"} Output: "bb"

def longest_palindrome(text: str) -> str:
    """Find the earliest longest palindrome by odd and even centers."""
    pass