func (a byKey) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
func (a byKey) Less(i, j int) bool { return a[i].key < a[j].key }

type ArchsByName []arch

func (x ArchsByName) Len() int           { return len(x) }
func (x ArchsByName) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }