code: function (latlngs) {
  		var result = [],
  		    flat = L.Polyline._flat(latlngs);
  
  		for (var i = 0, len = latlngs.length; i < len; i++) {
  			if (flat) {
  				result[i] = L.latLng(latlngs[i]);
  				this._bounds.extend(result[i]);
  			} else {
  				result[i] = this._convertLatLngs(latlngs[i]);
  			}
  		}
  
  		return result;
  	}
docs: recursively convert latlngs input into actual LatLng instances; calculate bounds along the way