gistfile1.txt

<?php

interface Baz
{
    public function BazBaz();
}

=========

interface Bar extends Baz
{
}

=========

class Dingo implements Bar
{
    public function BazBaz() {
        return true;
    }
}

=============

class Foo
{
    public function FooFoo(Baz $baz)
    {
    }
}

=========

$ding = new Foo;
$ding->FooFoo(new Dingo);