code: func WithTSL2561AutoGain(c Config) {
  	d, ok := c.(*TSL2561Driver)
  	if ok {
  		d.autoGain = true
  		return
  	}
  	// TODO: return errors.New("Trying to set Auto Gain for non-TSL2561Driver")
  }
docs: // WithTSL2561AutoGain option turns on TSL2561Driver auto gain