Check if Glib::RefPtr<Glib::VariantDict> class is empty or not

Question

I was wondering if there is a method such as variantDict.empty() or variantDict.size(). I looked it up from this website and couldn't find anything. https://developer.gnome.org/glibmm/stable/classGlib_1_1VariantDict.html#a867a56baa952c4f98ecf21b01d3d00c3

If someone knows a way of checking if the variantDict is empty or not, please kindly help me. Thanks!