code: public static MarkedElement markupMol(IRenderingElement elem, IAtomContainer mol) {
          assert elem != null;
          MarkedElement tagElem = markupChemObj(elem, mol);
          tagElem.aggClass("mol");
          return tagElem;
      }
docs: Markup a molecule with the class 'mol' and optionally the ids/classes
  from it's properties.
  
  @param elem rendering element
  @param mol molecule
  @return the marked element