lsb-sample3.php

<?php

// Solution 1. Let ElectricCar handle unplugging itself
class ElectricCar extends Car
{
  ...
  public function start()
  {
    $this->unplug(); 
    parent::start();
  }
  ...
}

// Solution 2. Change the interface
class Car
{
  public function BeforeStart()
  {
  }
  
  public function start()
  {
  }
}