code: func (a *ArgType) retype(typ string) string {
  	if strings.Contains(typ, ".") {
  		return typ
  	}
  
  	prefix := ""
  	for strings.HasPrefix(typ, "[]") {
  		typ = typ[2:]
  		prefix = prefix + "[]"
  	}
  
  	if _, ok := a.KnownTypeMap[typ]; !ok {
  		pkg := a.CustomTypePackage
  		if pkg != "" {
  			pkg = pkg + "."
  		}
  
  		return prefix + pkg + typ
  	}
  
  	return prefix + typ
  }
docs: // retype checks typ against known types, and prefixing
  // ArgType.CustomTypePackage (if applicable).