<?php
interface pump {
    function get_gas();
}

class premium implements pump {
    function get_gas() {
        echo "chug..chug..chug!\n<br />\n";
    }
}

class regular implements pump {
    function get_gas() {
        echo "chug..cough..chug..\n<br />\n";
    }
}

class mercedes {
    function infuse_gas(premium $pump) {
        echo "mercedes: ";
        $pump->get_gas();
    }
}

class pinto {
    function infuse_gas(pump $pump) {
        echo "pinto: ";
        $pump->get_gas();
    }
}

$pinto = new pinto;
$pinto->infuse_gas(new premium);
$pinto->infuse_gas(new regular);

$mercedes = new mercedes;
$mercedes->infuse_gas(new premium);
$mercedes->infuse_gas(new regular);
?>