public function removeLayer(Layer $layer)
    {
        $key = array_search($layer, $this->baseLayers);
        if ($key !== false) {
            unset($this->baseLayers[$key]);
        }

        $key = array_search($layer, $this->overlays);
        if ($key !== false) {
            unset($this->overlays[$key]);
        }

        return $this;
    }