code: public static String getCardType(String ccPassed) {
          if (isEmpty(ccPassed)) return "Unknown";
          String cc = stripCharsInBag(ccPassed, creditCardDelimiters);
  
          if (!isCreditCard(cc)) return "Unknown";
  
          if (isMasterCard(cc)) return "MasterCard";
          if (isVisa(cc)) return "Visa";
          if (isAmericanExpress(cc)) return "AmericanExpress";
          if (isDinersClub(cc)) return "DinersClub";
          if (isDiscover(cc)) return "Discover";
          if (isEnRoute(cc)) return "EnRoute";
          if (isJCB(cc)) return "JCB";
          return "Unknown";
      }
docs: Checks to see if the cc number is a valid number for any accepted credit card, and return the name of that type
  @param     ccPassed - a string representing a credit card number
  @return  true, if the credit card number is any valid credit card number for any of the accepted card types, false otherwise