static double threeB1BScore(int pos, int neg) {
  ret doubleRatio(pos+1, pos+neg+2)*100;
}

ifclass PosNeg
static double threeB1BScore(PosNeg pn) {
  ret pn == null ? 0 : threeB1BScore(l(pn.pos), l(pn.neg));
}
endif