static int lowerCaseCompare(S a, S b) {

  if (a == null) ret b == null ? 0 : -1;

  if (b == null) ret 1;

  int len1 = a.length();

  int len2 = b.length();

  int lim = Math.min(len1, len2);

  int k = 0;

  while (k < lim) {

    char c1 = Character.toLowerCase(a.charAt(k));

    char c2 = Character.toLowerCase(b.charAt(k));

    if (c1 != c2)

      ret c1 - c2;

    k++;

  }

  ret len1 - len2;

}