code: func (r *Router) SetEnv(name, value string) {
  	r.Lock()
  	defer r.Unlock()
  
  	env := os.Getenv(name)
  	if len(env) == 0 { env = value }
  	r.Set(name, env)
  }
docs: // SetEnv stores the specified environment variable as a key / value pair. If
  // the environment variable is not set the default value will be used