code: func StatBlobs(ctx context.Context, bs BlobStatter, blobs []blob.Ref) (map[blob.Ref]blob.SizedRef, error) {
  	var m map[blob.Ref]blob.SizedRef
  	err := bs.StatBlobs(ctx, blobs, func(sb blob.SizedRef) error {
  		if m == nil {
  			m = make(map[blob.Ref]blob.SizedRef)
  		}
  		m[sb.Ref] = sb
  		return nil
  	})
  	return m, err
  }
docs: // StatBlobs stats multiple blobs and returns a map
  // of the found refs to their sizes.