Function run 

pub fn run(
    src: Box<dyn Source>,
    viewport: Viewport,
    idx: LineIndex,
    sigterm: Arc<AtomicBool>,
    rebuild_spec: RebuildSpec,
    keymap: KeyMap,
    file_set: FileSet,
    record_start_regex: Option<Regex>,
    args: Args,
    preprocessor: Option<Preprocessor>,
    tag_file: Option<TagFile>,
) -> Result<()>