code: func NewBotFromAgentFile(filename string, rate time.Duration) (Bot, error) {
  	agent, app, err := load(filename)
  	if err != nil {
  		return nil, err
  	}
  
  	return NewBot(
  		BotConfig{
  			Agent: agent,
  			App:   app,
  			Rate:  rate,
  		},
  	)
  }
docs: // NewBotFromAgentFile calls NewBot with a config built from an agent file. An
  // agent file is a convenient way to store your bot's account information. See
  // https://github.com/turnage/graw/wiki/agent-files