public IBlock FindNodeById(string id) { if (id == ID) { return(this); } else { if (null != Molecule) { var node = Molecule.FindNodeById(id); if (null != node) { return(node); } } if (null != Denominator) { var deNode = Denominator.FindNodeById(id); if (null != deNode) { return(deNode); } } return(null); } }