code: @Override
      public boolean contains(IAtomContainer ring) {
          for (int i = 0; i < getAtomContainerCount(); i++) {
              if (ring == getAtomContainer(i)) {
                  return true;
              }
          }
          return false;
      }
docs: Checks for presence of a ring in this RingSet.
  
  @param  ring  The ring to check
  @return  true if ring is part of RingSet