code: static boolean isValidMonth(@Nullable String monthString) {
          if (monthString == null) {
              return false;
          }
  
          try {
              int monthInt = Integer.parseInt(monthString);
              return monthInt > 0 && monthInt <= 12;
          } catch (NumberFormatException numEx) {
              return false;
          }
      }
docs: Checks to see if the string input represents a valid month.
  
  @param monthString user input representing the month
  @return {@code true} if the string is a number between "01" and "12" inclusive,
  {@code false} otherwise