code: @Override
      public boolean applyAction(Model m) {
          Mapping map = m.getMapping();
  
          if (!map.contains(id)) {
              map.addReadyVM(id);
              return true;
          }
          return false;
      }
docs: Put the VM in the ready state iff
  it does not already belong to the mapping.
  
  @param m the model to modify
  @return {@code true} iff successful