code: public static boolean isLetter(int ch)
      {
          // if props == 0, it will just fall through and return false
          return ((1 << getType(ch))
                  & ((1 << UCharacterCategory.UPPERCASE_LETTER)
                          | (1 << UCharacterCategory.LOWERCASE_LETTER)
                          | (1 << UCharacterCategory.TITLECASE_LETTER)
                          | (1 << UCharacterCategory.MODIFIER_LETTER)
                          | (1 << UCharacterCategory.OTHER_LETTER))) != 0;
      }
docs: Determines if the specified code point is a letter.
  Up-to-date Unicode implementation of java.lang.Character.isLetter()
  @param ch code point to determine if it is a letter
  @return true if code point is a letter