get_v_kerning(hb_font_t *font, void *font_data, hb_codepoint_t first,
                 hb_codepoint_t second, void *user_data)
{
    return 0;
}
get_v_kerning(hb_font_t *font, void *font_data, hb_codepoint_t first,
                 hb_codepoint_t second, void *user_data)
{
    return 0;
}