ISP (Interface Segregation Principle) good practice

ispGood.php

<?php

interface MachineInterface
{
	public function open();
	
	public function heatWater();
	
}

interface CoffeeMachineInterface extends MachineInterface
{
	public function makeCoffee();
}

interface TeaMachineInterface extends MachineInterface
{
	public function makeTea();
}

class CoffeeMachine implements CoffeeMachineInterface
{
	
	public function open()
	{
		return 'Machine is opening';
	}
	
	public function heatWater()
	{
		return 'Water is heating';
	}
	
	public function makeCoffee()
	{
		return 'Coffee is making';
	}
	
}