strings.Contains(value, ",") {
				return nil, ErrHeader
			}
			sparseMap = append(sparseMap, value)
		default:
			paxHdrs[key] = value
		}
	}
	if len(sparseMap) > 0 {
		paxHdrs[paxGNUSparseMap] = strings.Join(sparseMap, ",")
	}
	return paxHdrs, nil
}

// readHeader reads the next block header and assumes that the underlying reader

		Reader: wrapped,
	}
}

// A Reader wraps an io.Reader and computes the
// MD5 checksum of the read content as ETag.
//
// Optionally, a Reader can also verify that
// the computed ETag matches an expected value.
// Therefore, it compares both ETags once the
// underlying io.Reader returns io.EOF.
// If the computed ETag does not match the
// expected ETag then Read returns a VerifyError.
//