code: func (s ShapeTags) Join(sep string) string {
  	o := &bytes.Buffer{}
  	for i, t := range s {
  		o.WriteString(t.String())
  		if i < len(s)-1 {
  			o.WriteString(sep)
  		}
  	}
  
  	return o.String()
  }
docs: // Join returns an ordered serialization of the shape tags with the provided
  // separator.