code: function (obj) { // (LatLng) or (LatLngBounds)
  		if (!obj) { return this; }
  
  		var latLng = L.latLng(obj);
  		if (latLng !== null) {
  			obj = latLng;
  		} else {
  			obj = L.latLngBounds(obj);
  		}
  
  		if (obj instanceof L.LatLng) {
  			if (!this._southWest && !this._northEast) {
  				this._southWest = new L.LatLng(obj.lat, obj.lng);
  				this._northEast = new L.LatLng(obj.lat, obj.lng);
  			} else {
  				this._southWest.lat = Math.min(obj.lat, this._southWest.lat);
  				this._southWest.lng = Math.min(obj.lng, this._southWest.lng);
  
  				this._northEast.lat = Math.max(obj.lat, this._northEast.lat);
  				this._northEast.lng = Math.max(obj.lng, this._northEast.lng);
  			}
  		} else if (obj instanceof L.LatLngBounds) {
  			this.extend(obj._southWest);
  			this.extend(obj._northEast);
  		}
  		return this;
  	}
docs: extend the bounds to contain the given point or bounds