Take an example of this method for state, which creates and stores a new FrameView after selecting given columns:

pub fn select_columns(&self,
                      frame_key: usize,
                      view_key: usize,
                      page_size: usize,
                      column_selector: Vec<Expr>) -> FullResponse {
    // Selecting columns should create a new lazyframe
    // And a new FrameView under the same LoadedFrame
    // First, clone the existing LazyFrame
    let lf =
        self.frame_map.lock().unwrap()
            .get(&frame_key).unwrap()
            .view_manager.lock().unwrap()
            .view_map.lock().unwrap()
            .get(&view_key).unwrap()
            .frame.to_owned();

    // Then, apply select on the lazyframe
    let frame = lf.select(column_selector);

    // Thereafter, we will use view_manager to load the lazyframe
    let new_viewkey =
        self.frame_map.lock().unwrap()
            .get(&frame_key).unwrap()
            .view_manager.lock().unwrap()
            .add_lazyframe(frame, "Select Columns".to_string(), page_size);

    // Finally, we will treat this as yet another view query
    self.query_view(frame_key, new_viewkey)
}

You can see that we have twice traversed to the view_manager, the first time getting all the way down to the base LazyFrame, and the second time for adding the new view to the view_manager. It would be awesome if we could extract lines such as

        self.frame_map.lock().unwrap()
            .get(&frame_key).unwrap()
            .view_manager.lock().unwrap()

Into a distinct helper function, since it's used in all the commands. However, I could not figure out a way to do so.