PHP program to implement an interface into multiple classes

<?php
//PHP program to implement an interface 
//into multiple classes.
interface Inf
{
    public function fun();
}

class Sample1 implements Inf
{
    public function fun()
    {
        printf("Sample1::fun() called<br>");
    }
}

class Sample2 implements Inf
{
    public function fun()
    {
        printf("Sample2::fun() called<br>");
    }
}

class Sample3 implements Inf
{
    public function fun()
    {
        printf("Sample3::fun() called<br>");
    }
}

$obj1 = new Sample1();
$obj2 = new Sample2();
$obj3 = new Sample3();

$obj1->fun();
$obj2->fun();
$obj3->fun();
?>

Output
Sample1::fun() called
Sample2::fun() called
Sample3::fun() called