Someone is claiming they wrote this code [on hold]

I'm close to releasing my app and my friend added the collision-detection code in the beginning. If this looks familiar please let me know:

    function collides(a, b) {
var aTop = a.offset().top;
var aLeft = a.offset().left;
var bTop = b.offset().top;
var bLeft = b.offset().left;

return !(
    ((aTop + a.height()) < (bTop)) ||
    (aTop > (bTop + b.height())) ||
    ((aLeft + a.width()) < bLeft) ||
    (aLeft > (bLeft + b.width()))
);
}
 //colliding stuff and responce.
    function handleCollisions() {
    if (collides($('#firstObs'),$('#player'))) {
        $('#levelOne').stop();
 $('#player').css('border', 'solid 1px red');             
      }
    else { // if not collision
        $('#player').html("<p></p>");
    }
}      

Is there a source on the web that he might of got this code from, to prove he did write it himself?