code: func AddBanner(build *ui.MiloBuildLegacy, tags strpair.Map) {
  	os := tags.Get("os")
  	parts := strings.SplitN(os, "-", 2)
  	var ver string
  	if len(parts) == 2 {
  		os = parts[0]
  		ver = parts[1]
  	}
  
  	var base ui.LogoBase
  	switch os {
  	case "Ubuntu":
  		base = ui.Ubuntu
  	case "Windows":
  		base = ui.Windows
  	case "Mac":
  		base = ui.OSX
  	case "Android":
  		base = ui.Android
  	default:
  		return
  	}
  	build.Summary.Banner = &ui.LogoBanner{
  		OS: []ui.Logo{{
  			LogoBase: base,
  			Subtitle: ver,
  			Count:    1,
  		}},
  	}
  }
docs: // AddBanner adds an OS banner derived from "os" swarming tag, if present.