static double scoreRegexpIC(S regexp, Cl<S> pos, Cl<S> neg) {
  PosNegMatrix<LS> matrix = posNegMatrixForRegexpIC(regexp, pos, neg);
  PosNegMatrix<Int> m2 = posNegMatrixOfLists_lengths(matrix);
  double quality = posNegMatrixOfInts_quality(m2);
  //if (verbose) print(regexp + ": " + m2 + " / " + quality);
  ret quality;
}