Tetris

Okay, we're now ready to start writing down our tetris!

First, let's fulfill our main.rs file in order to check whether everything is working as expected:

    extern crate sdl2;

    use sdl2::pixels::Color;
    use sdl2::event::Event;
    use sdl2::keyboard::Keycode;
    use std::time::Duration;
    use std::thread::sleep;

    pub fn main() {
      let sdl_context = sdl2::init().expect("SDL initialization   
      failed");
      let video_subsystem = sdl_context.video().expect("Couldn't get 
       SDL video subsystem");

      let window = video_subsystem.window("rust-sdl2 demo: Video", 800,
            600)
        .position_centered()
        .opengl()
        .build()
        .expect("Failed to create window");

      let mut canvas = window.into_canvas().build().expect("Failed to
        convert window into...