code: func computeDiscoverCacheDir(parentDir, host string) string {
  	// strip the optional scheme from host if its there:
  	schemelessHost := strings.Replace(strings.Replace(host, "https://", "", 1), "http://", "", 1)
  	// now do a simple collapse of non-AZ09 characters.  Collisions are possible but unlikely.  Even if we do collide the problem is short lived
  	safeHost := overlyCautiousIllegalFileCharacters.ReplaceAllString(schemelessHost, "_")
  	return filepath.Join(parentDir, safeHost)
  }
docs: // computeDiscoverCacheDir takes the parentDir and the host and comes up with a "usually non-colliding" name.