/**
     * checkBalance - an aid method:
     * will check if a given string is balanced, recursively, with the help of another strings
     * @param str1 - the given string to check.
     * @param openBrackets - will store the open brackets found in str1
     * @return true - if the given string is balanced, false - if the given string isn't balanced.
     */
    public static boolean checkBalance(String str1, String openBrackets){

        int a = bracketIndex(str1);

        if ( a == -1 ){
            return openBrackets.isEmpty();
        }//if

        if( isItOpen(str1.charAt(a)) == true )
        {
            return checkBalance(str1.substring(a+1), openBrackets + str1.charAt(a));
        }//if
        else{
            if ( openBrackets.length() == 0){
                return false;
            }//if

            if( checkBracket( openBrackets.charAt(openBrackets.length()-1), str1.charAt(a) ) == true ) {
                return checkBalance(str1.substring(a+1), openBrackets.substring(0, openBrackets.length()-1));
            }//if

        }//else

        return false;
    }//end of checkBalance

    /**
     * isBalanced - 3rd Method:
     * will check if a given string is balanced, using an aid method that gets two strings (according to the hint)
     * @param str - the string to be checked.
     * @return true - if the given string is balanced.
     */
    public static boolean isBalanced(String str) {
        return checkBalance(str, "");
    }//end of isBalanced