libmachine/drivers/serial.go
func (d *SerialDriver) GetSSHPort() (int, error) {
	d.Lock()
	defer d.Unlock()
	return d.Driver.GetSSHPort()
}
func (d *SerialDriver) GetSSHPort() (int, error) {
	d.Lock()
	defer d.Unlock()
	return d.Driver.GetSSHPort()
}
// GetSSHPort returns port for use with ssh