public static boolean isPositive(int c) {
        return (c & 1) == 1;
    }
Conjunction id format:
  bit 31-1:  id/hash
  bit 0:     0: negated, 1: not negated

@author bjorncs
predicate-search/src/main/java/com/yahoo/search/predicate/index/conjunction/ConjunctionId.java