code: func (bh *Header) Tags(fn func(t Tag, value string)) {
  	if fn == nil {
  		return
  	}
  	fn(versionTag, bh.Version)
  	if bh.SortOrder != UnknownOrder {
  		fn(sortOrderTag, bh.SortOrder.String())
  	}
  	if bh.GroupOrder != GroupNone {
  		fn(groupOrderTag, bh.GroupOrder.String())
  	}
  	for _, tp := range bh.otherTags {
  		fn(tp.tag, tp.value)
  	}
  }
docs: // Tags applies the function fn to each of the tag-value pairs of the Header.
  // The SO and GO tags are only used if they are set to the non-default values.
  // The function fn must not add or delete tags held by the receiver during
  // iteration.