<?php 

class SellerProxy {

    public function sellVehicle(Vehicle $vehicle) {

        $this->irma->sell???($vehicle);

    }

} 

<?php 

class FractionRelle implements Fraction, Nombre{

}

class EntierPositif implements Entier, Nombre {

}



class Additition {

    public function add(Nombre $n, Nombre $p) {

         // ??

    }

    private function add(Fraction $f, Entier $e) {

        // Do calc stuff

        return new Fraction|Entier(); // Depends on the calculation

    }

    private function add(Complexe $c, Nombre $n) {

        // other calcs

    }

    // ... And other private calculation methods

}