code: func (d *MCP3004Driver) Start() (err error) {
  	bus := d.GetBusOrDefault(d.connector.GetSpiDefaultBus())
  	chip := d.GetChipOrDefault(d.connector.GetSpiDefaultChip())
  	mode := d.GetModeOrDefault(d.connector.GetSpiDefaultMode())
  	bits := d.GetBitsOrDefault(d.connector.GetSpiDefaultBits())
  	maxSpeed := d.GetSpeedOrDefault(d.connector.GetSpiDefaultMaxSpeed())
  
  	d.connection, err = d.connector.GetSpiConnection(bus, chip, mode, bits, maxSpeed)
  	if err != nil {
  		return err
  	}
  	return nil
  }
docs: // Start initializes the driver.