pub type AppResult<T> = std::result::Result<T, Box<dyn std::error::Error>>;

pub struct App<'a> {
    pub running: bool,
    pub tabs: Vec<&'a str>,
    pub tab_index: usize,
}

impl<'a> App<'a> {
    pub fn new() -> App<'a> {
        App {
            running: true,

            tabs: vec!["Tab1", "Tab2", "Tab3"],
            tab_index: 0,
        }
    }

    pub fn next_tab(&mut self) {
        self.tab_index = (self.tab_index + 1) % self.tabs.len();
    }

    pub fn prev_tab(&mut self) {
        if self.tab_index > 0 {
            self.tab_index -= 1;
        } else {
            self.tab_index = self.tabs.len() - 1;
        }
    }}