sclass BoolGuesserByWordAtIndex extends F1<S, Bool> {
  bool defaultValue;
  Set<S> exceptions;
  int wordIndex;
  
  *() {}
  *(bool *defaultValue, Set<S> *exceptions, int *wordIndex) {}
  
  Bool get(S s) {
    ret defaultValue ^ contains(exceptions, getWord(s, wordIndex));
  }
}

static F1<S, Bool> boolGuesserByWordAtIndex(Map<S, Bool> examples, final int wordIndex) {
  Map<S, Bool> map = mapKeys(examples, func(S s) { getWord(s, wordIndex) });
  int diff = countValues(map, true)-countValues(map, false);
  print("diff=" + diff);
  final bool defaultValue = diff > 0;
  final Set<S> exceptions = new TreeSet(keysWithValue(map, !defaultValue));
  ret BoolGuesserByWordAtIndex(defaultValue, exceptions, wordIndex);
}