GST_IS_ELEMENT_CLASS 1199 gst/gstelement.c   g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
GST_IS_ELEMENT_CLASS 1239 gst/gstelement.c   g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
GST_IS_ELEMENT_CLASS 1276 gst/gstelement.c   g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
GST_IS_ELEMENT_CLASS 1296 gst/gstelement.c   g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
GST_IS_ELEMENT_CLASS 1320 gst/gstelement.c   g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
GST_IS_ELEMENT_CLASS 2563 gst/gstutils.c   g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));