Discuss an algorithm to traverse a tree, depth first.

Write a function that takes an integer and returns the smallest number that is greater than the given number which is a palendrome.

For example, if the input was 111 the next palindromic number would be 121.

Write a function, tokenize_string(input_string, delimiter_list) that returns a list of strings that are separated by the delimiters.

For example: tokenize_string("How now, Mrs. Brown Cow") returns ['How', 'now', 'Mrs', 'Brown', 'Cow']

Write a function that takes as input two numbers represented as strings, and returns the product of the numbers of a string.

The numbers can be arbitrarily large.

Write a function that takes a an array of integers, and returns the contiguous subsequence of integers with the largest sum.