code: public static ComputationGraph loadCheckpointCG(File rootDir, int checkpointNum){
          File f = getFileForCheckpoint(rootDir, checkpointNum);
          try {
              return ModelSerializer.restoreComputationGraph(f, true);
          } catch (IOException e){
              throw new RuntimeException(e);
          }
      }
docs: Load a ComputationGraph for the given checkpoint that resides in the specified root directory
  
  @param rootDir       Directory that the checkpoint resides in
  @param checkpointNum Checkpoint model number to load
  @return The loaded model