code: func CssProviderGetDefault() (*CssProvider, error) {
  	c := C.gtk_css_provider_get_default()
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	obj := glib.Take(unsafe.Pointer(c))
  	return wrapCssProvider(obj), nil
  }
docs: // CssProviderGetDefault is a wrapper around gtk_css_provider_get_default().