code: func (e *Adaptor) GetConnection(address int, bus int) (connection i2c.Connection, err error) {
  	e.mutex.Lock()
  	defer e.mutex.Unlock()
  
  	if !(bus == e.GetDefaultBus()) {
  		return nil, errors.New("Unsupported I2C bus")
  	}
  	if e.i2cBus == nil {
  		if bus == 6 && e.board == "arduino" {
  			e.arduinoI2CSetup()
  		}
  		e.i2cBus, err = sysfs.NewI2cDevice(fmt.Sprintf("/dev/i2c-%d", bus))
  	}
  	return i2c.NewConnection(e.i2cBus, address), err
  }
docs: // GetConnection returns an i2c connection to a device on a specified bus.
  // Valid bus numbers are 1 and 6 (arduino).