code: func (t *NetworkDevice) Hash() uint64 {
  	h := fnv.New64a()
  	fmt.Fprintf(h, "%s\n%s\n%s\n%s",
  		t.Metro,
  		t.Role,
  		t.Hostname,
  		t.Hostgroup)
  	return h.Sum64()
  }
docs: // Hash returns a uint64 hash of this target.