public void addCell(Cell cell) {
   if (!stringToCellID.containsKey(cell.getName())) {
     stringToCellID.put(cell.getName(), cell.getCellID());
   } else {
     return; // return gracefully.
   }
 }
 public void removeCell(Cell cell) {
   if (stringToCellID.containsKey(cell.getName())) {
     stringToCellID.remove(cell.getName());
   } else {
     return; // return gracefully
   }
 }
  /** Adds the movable component, assumes it does not already exist. */
  private void addMovableComponent(Cell cell) {

    // Go ahead and try to add the affordance. If we cannot, then log an
    // error and return.
    CellID cellID = cell.getCellID();
    String className = "org.jdesktop.wonderland.server.cell.MovableComponentMO";
    CellServerComponentMessage cscm = CellServerComponentMessage.newAddMessage(cellID, className);
    ResponseMessage response = cell.sendCellMessageAndWait(cscm);
    if (response instanceof ErrorMessage) {
      LOGGER.warning(
          "Unable to add movable component for Cell"
              + cell.getName()
              + " with ID "
              + cell.getCellID());
    }
  }