Validation is a method that takes in a string, goes through it character by character and verifies that all opening brackets have a matching closing bracket (and vise versa).
Write a method that takes in a string, and validates whether or not it has the correct sequence of brackets. Return true for correctly formatted strings and false for incorrectly formatted strings.
The method built iterates through the string one character at a time pushing openning brackets into a stack and validating order of closing brackets against that stack. it is O(n) for time and space in worst case.
