run.ts

interface Car {
    run(fuel: string);
}
interface Human {
    run(distance: number);
}

// Makes the specified object go
// run := (Car, string)
// run := (Human, number)
public void run(obj, v) {
    if( typeof v === 'string' ) {
        (<Car>obj).run(fuel);
    } else {
        (<Human>obj).run(dist);
    }
}