libmachine/drivers/serial.go
func (d *SerialDriver) GetSSHUsername() string {
	d.Lock()
	defer d.Unlock()
	return d.Driver.GetSSHUsername()
}
func (d *SerialDriver) GetSSHUsername() string {
	d.Lock()
	defer d.Unlock()
	return d.Driver.GetSSHUsername()
}
// GetSSHUsername returns username for use with ssh