Check multiple implementation

app.php

<?php

interface iA
{
    public function someA();
    public function thisIs();
}

interface iB
{
    public function someB();
    public function thisIs();
}

class A implements iA
{
    public function someA() {}
    public function thisIs() {}
}

class B implements iB
{
    public function someB() {}
    public function thisIs() {}
}

class AB implements iA, iB
{
    public function someA() {}
    public function someB() {}
    public function thisIs() {}
}

$a = new A;
$b = new B;
$ab = new AB;