Leaflet z index (markers)

HTML

<script src="https://maps.google.com/maps/api/js?sensor=false&amp;dummy=.js"></script>
<link rel="stylesheet" href="//cdn.leafletjs.com/leaflet-0.7.3/leaflet.css">
<script src="//cdn.leafletjs.com/leaflet-0.7.3/leaflet.js"></script>
<body>
<div id="map" ></div>
</body>

CSS

html, body, #map {
        margin: 0;
        width: 100%;
        height: 100%;
}

JavaScript

var pos1 = new L.LatLng(45.5,-73.5);
var pos2 = new L.LatLng(45.5002,-73.5002);

var map = new L.Map('map', {
                center: pos1,
                zoom: 16,
               // markerZoomAnimation:false
            });

L.tileLayer('http://{s}.tile.osm.org/{z}/{x}/{y}.png', {attribution: '&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'}).addTo(map);

var icon1 = L.marker(pos1);
var icon2 = L.marker(pos2);

//v1 does not work:
//icon1.setZIndexOffset(1000);
//icon2.setZIndexOffset(1);
icon1.addTo(map);
icon2.addTo(map);
icon1.setZIndex(1000);
icon2.setZIndex(1);



//v2 does not work:
//var iconLayer1 = L.layerGroup([icon1]);
//var iconLayer2 = L.layerGroup([icon2]);
//iconLayer1.setZIndex(2000);
//iconLayer2.setZIndex(1000);
//iconLayer2.addTo(map);
//iconLayer1.addTo(map);

//v3 
//var iconLayer1 = L.featureGroup([icon1]);
//var iconLayer2 = L.featureGroup([icon2]);
//iconLayer2.addTo(map);
//iconLayer1.addTo(map);
//debugger;
//iconLayer1.setStyle("zIndex", 100000)
//iconLayer1.setStyle("z-index", 100000)
//iconLayer1.bringToFront();