return false; }
    public boolean push(UniqueObject uo) {      if (uo != null) {        UID uid = uo.getUID();        if (m.put(uid, uo) == null) {          // add if new          l.add(uo);          if (VERBOSE) {            System.out.println(			       "++++pushed UID: "+uid+" for "+uo.getClass().getName());          }          return true;        } else {          if (VERBOSE) {            System.out.println(			       "    ignore UID: "+uid+" for "+uo.getClass().getName());          }        }      } else {        if (VERBOSE) {          System.out.println("    ignore null");        }      }      return false;    }