You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/orbtk/orbtk_widgets/src/themes/theme_orbtk
    
    the code of the file until where you have to start completion: /*!

This submodule provides the default theme resources of OrbTks default theme dark 
    
pub fn theme_default_dark() -> Theme {
    register_default_fonts(Theme::from_config(
        ThemeConfig::from(THEME_DEFAULT)
            .extend(ThemeConfig::from(THEME_DEFAULT_COLORS_DARK))
            .extend(ThemeConfig::from(THEME_DEFAULT_FONTS))
            .extend(ThemeConfig::from(MATERIAL_ICONS)),
    ))
}