code: @Override
      public boolean matches(IAtom atom) {
  
          if (!((IQueryAtom) query.getAtom(0)).matches(atom)) return false;
  
          if (query.getAtomCount() == 1) return true;
  
          IAtomContainer target = invariants(atom).target();
  
          return cache.getUnchecked(target).get(target.indexOf(atom));
      }
docs: /*
  (non-Javadoc)
  @see
  org.openscience.cdk.isomorphism.matchers.smarts.SMARTSAtom#matches(org
  .openscience.cdk.interfaces.IAtom)