code: private static void resetCounters() {
          atomCount = 0;
          bondCount = 0;
          atomContainerCount = 0;
          atomContainerSetCount = 0;
          reactionCount  = 0;
          reactionSetCount = 0;
          chemModelCount = 0;
          chemSequenceCount = 0;
          chemFileCount = 0;
      }
docs: Reset the counters so that we keep generating simple IDs within
  single chem object or a set of them