code: func registerAlias(name, alias string, doSort bool) {
  	scheme, ok := schemeMap[name]
  	if !ok {
  		panic(fmt.Sprintf("scheme %s not registered", name))
  	}
  
  	if doSort && has(scheme.Aliases, alias) {
  		panic(fmt.Sprintf("scheme %s already has alias %s", name, alias))
  	}
  
  	if _, ok := schemeMap[alias]; ok {
  		panic(fmt.Sprintf("scheme %s already registered", alias))
  	}
  
  	scheme.Aliases = append(scheme.Aliases, alias)
  	if doSort {
  		sort.Sort(ss(scheme.Aliases))
  	}
  
  	schemeMap[alias] = scheme
  }
docs: // registerAlias registers a alias for an already registered Scheme.