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: main.rs
    path of file: ./repos/glium/examples/spirv
    
    the code of the file until where you have to start completion: // This example demonstrates SPIR-V shader loading.
// It's based on the screenshot example but uses an empty vertex buffer.

#[macro_use]
extern crate glium;

use std::num::NonZeroU32;
use glium::index::PrimitiveType;
use glium::program::{SpirvEntryPoint, ProgramCreationInput, SpirvProgram};
use glium::{Surface};
use glutin::context::Version;
use glutin::prelude::*;
use glutin::display::GetGlDisplay;
use glutin::surface::WindowSurface;
use raw_window_handle::HasRawWindowHandle;

fn main() {
    // We start by creating the main EventLoop
    let event_loop = winit::event_loop::EventLoopBuilder::new()
        .build()
        .expect("event loop building");
    let window_builder = winit::window::WindowBuilder::new().with_title("Glium SPIR-V example");
    let config_template_builder = glutin::config::ConfigTemplateBuilder::new();
    let display_builder = glutin_winit::DisplayBuilder::new().with_window_builder(Some(window_builder));

    // Now we need to create a window
    let (window, gl_config) = display_builder
        .build(&event_loop, config_template_builder, |mut configs| {
            // Just use the first configuration since we don't have any special preferences
            configs.next().unwrap()
        })
        .unwrap();
    let window = window.unwrap();

    // Then the configuration which decides which OpenGL version we'll end up using, here we just use the default which is currently 3.3 core
    let raw_window_handle = window.raw_window_handle();
    // We need a 4.6 context for SPIR-V support
    let context_attributes = glutin::context::ContextAttributesBuilder::new()
        .with_context_api(glutin::context::ContextApi::OpenGl(Some(Version::new(4, 6))))
        .build(Some(raw_window_handle));

    let not_current_gl_context = Some(unsafe {
        gl_config.display().create_context(&gl_config, &context_attributes).expect("failed to create context")
    });

    // Determine our framebuffer size based on the window size
    let (width, height): (u32, u32) = window.inner_size().into();
    let attrs = glutin::surface::SurfaceAttributesBuilder::<WindowSurface>::new().build(
        raw_window_handle,
        NonZeroU32::new(width).unwrap(),
        NonZeroU32::new(height).unwrap(),
    );
    // Now we can create our surface, use it to make our context current and finally create our display
    let surface = unsafe { gl_config.display().create_window_surface(&gl_config, &attrs).unwrap() };
    let current_context = not_current_gl_context.unwrap().make_current(&surface).unwrap();
    let display = glium::Display::from_context_surface(current_context, surface).unwrap();

    // building the vertex buffer with no vertices
    // https://www.saschawillems.de/blog/2016/08/13/vulkan-tutorial-on-rendering-a-fullscreen-quad-without-buffers/
    let vertex_buffer = {
        #[derive(Copy, Clone)]
        struct Vertex {
            dummy: f32,
        }

        implement_vertex!(Vertex, dummy);

        glium::VertexBuffer::<Vertex>::empty(&display, 0).unwrap()
    };

    // building the index buffer
    let index_buffer = glium::IndexBuffer::new(&display, PrimitiveType::TrianglesList,
                                               &[0u8, 1, 2]).unwrap();

    // loading SPIR-V module that contains fragment and vertex shader entry points both called "main"
    let spirv = SpirvEntryPoint { binary: include_bytes!("shader.spv"), entry_point: "main" };
    let program = glium::Program::new(
        &display,
        ProgramCreationInput::SpirV(SpirvProgram::from_vs_and_fs(spirv, spirv))
    ).unwrap();

  
    
fn main() {
    // We start by creating the main EventLoop
    let event_loop = winit::event_loop::EventLoopBuilder::new()
        .build()
        .expect("event loop building");
    let window_builder = winit::window::WindowBuilder::new().with_title("Glium SPIR-V example");
    let config_template_builder = glutin::config::ConfigTemplateBuilder::new();
    let display_builder = glutin_winit::DisplayBuilder::new().with_window_builder(Some(window_builder));

    // Now we need to create a window
    let (window, gl_config) = display_builder
        .build(&event_loop, config_template_builder, |mut configs| {
            // Just use the first configuration since we don't have any special preferences
            configs.next().unwrap()
        })
        .unwrap();
    let window = window.unwrap();

    // Then the configuration which decides which OpenGL version we'll end up using, here we just use the default which is currently 3.3 core
    let raw_window_handle = window.raw_window_handle();
    // We need a 4.6 context for SPIR-V support
    let context_attributes = glutin::context::ContextAttributesBuilder::new()
        .with_context_api(glutin::context::ContextApi::OpenGl(Some(Version::new(4, 6))))
        .build(Some(raw_window_handle));

    let not_current_gl_context = Some(unsafe {
        gl_config.display().create_context(&gl_config, &context_attributes).expect("failed to create context")
    });

    // Determine our framebuffer size based on the window size
    let (width, height): (u32, u32) = window.inner_size().into();
    let attrs = glutin::surface::SurfaceAttributesBuilder::<WindowSurface>::new().build(
        raw_window_handle,
        NonZeroU32::new(width).unwrap(),
        NonZeroU32::new(height).unwrap(),
    );
    // Now we can create our surface, use it to make our context current and finally create our display
    let surface = unsafe { gl_config.display().create_window_surface(&gl_config, &attrs).unwrap() };
    let current_context = not_current_gl_context.unwrap().make_current(&surface).unwrap();
    let display = glium::Display::from_context_surface(current_context, surface).unwrap();

    // building the vertex buffer with no vertices
    // https://www.saschawillems.de/blog/2016/08/13/vulkan-tutorial-on-rendering-a-fullscreen-quad-without-buffers/
    let vertex_buffer = {
        #[derive(Copy, Clone)]
        struct Vertex {
            dummy: f32,
        }

        implement_vertex!(Vertex, dummy);

        glium::VertexBuffer::<Vertex>::empty(&display, 0).unwrap()
    };

    // building the index buffer
    let index_buffer = glium::IndexBuffer::new(&display, PrimitiveType::TrianglesList,
                                               &[0u8, 1, 2]).unwrap();

    // loading SPIR-V module that contains fragment and vertex shader entry points both called "main"
    let spirv = SpirvEntryPoint { binary: include_bytes!("shader.spv"), entry_point: "main" };
    let program = glium::Program::new(
        &display,
        ProgramCreationInput::SpirV(SpirvProgram::from_vs_and_fs(spirv, spirv))
    ).unwrap();

    // drawing once

    // building the uniforms
    let uniforms = uniform! {
        matrix: [
            [1.0, 0.0, 0.0, 0.0],
            [0.0, 1.0, 0.0, 0.0],
            [0.0, 0.0, 1.0, 0.0],
            [0.0, 0.0, 0.0, 1.0f32]
        ]
    };

    // drawing a frame
    let mut target = display.draw();
    target.clear_color(0.0, 0.0, 0.0, 0.0);
    target.draw(&vertex_buffer, &index_buffer, &program, &uniforms, &Default::default()).unwrap();
    target.finish().unwrap();

    // reading the front buffer into an image
    let image: glium::texture::RawImage2d<'_, u8> = display.read_front_buffer().unwrap();
    let image = image::ImageBuffer::from_raw(image.width, image.height, image.data.into_owned()).unwrap();
    let image = image::DynamicImage::ImageRgba8(image).flipv();
    image.save("glium-example-screenshot.png").unwrap();
}