the question ask you to write a method to find the linges palindrome form the given string
palindrome is if a word is read in reverse string it spells the same
example abba - is same if read in reverse

so if a string is given as "hello world abba, that is kayak"
in here there are 2 palindrome (substring) abba and kayak but the longest one is kayak (length of 5)

so writing a function to find the longest palindrome and return it