code: private String parseCurrencyCode(String token) {
          int letterIndex = 0;
          for (char ch : token.toCharArray()) {
              if (Character.isLetter(ch)) {
                  letterIndex++;
              } else {
                  return token.substring(0, letterIndex);
              }
          }
          return token;
      }
docs: Tries to split up a letter based first part, e.g. for evaluating a ISO currency code from an input as
  'CHF100.34'.
  @param token the input token
  @return the first letter based part, or the full token.