code: function (latlngs, result, projectedBounds) {
  		var flat = latlngs[0] instanceof L.LatLng,
  		    len = latlngs.length,
  		    i, ring;
  
  		if (flat) {
  			ring = [];
  			for (i = 0; i < len; i++) {
  				ring[i] = this._map.latLngToLayerPoint(latlngs[i]);
  				projectedBounds.extend(ring[i]);
  			}
  			result.push(ring);
  		} else {
  			for (i = 0; i < len; i++) {
  				this._projectLatlngs(latlngs[i], result, projectedBounds);
  			}
  		}
  	}
docs: recursively turns latlngs into a set of rings with projected coordinates