code: func (d *Dataset) GetTotalSize() int64 {
  	if d.Meta.TotalSize >= 0 {
  		return d.Meta.TotalSize
  	}
  	var currentDatasetTotalSize int64
  	for _, ds := range d.Step.InputDatasets {
  		currentDatasetTotalSize += ds.GetTotalSize()
  	}
  	d.Meta.TotalSize = currentDatasetTotalSize
  	return currentDatasetTotalSize
  }
docs: // GetTotalSize returns the total size in MB for the dataset.
  // This is based on the given hint.