rsvg_metadata_props_enumerate (const char *key, const char *value, gpointer user_data)
{
    GString *metadata = (GString *) user_data;
    g_string_append_printf (metadata, "%s=\"%s\" ", key, value);
}
rsvg_metadata_props_enumerate (const char *key, const char *value, gpointer user_data)
{
    GString *metadata = (GString *) user_data;
    g_string_append_printf (metadata, "%s=\"%s\" ", key, value);
}