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: mod.rs
    path of file: ./repos/wgpu/examples/src/shadow
    
    the code of the file until where you have to start completion: use std::{borrow::Cow, f32::consts, iter, mem, ops::Range, sync::Arc};

use bytemuck::{Pod, Zeroable};
use wgpu::util::{align_to, DeviceExt};

#[repr(C)]
#[derive(Clone, Copy, Pod, Zeroable)]
struct Vertex {
    _pos: [i8; 4],
    _normal: [i8; 4],
}

fn vertex(pos: [i8; 3], nor: [i8; 3]) -> Vertex {
    Vertex {
        _pos: [pos[0], pos[1], pos[2], 1],
        _normal: [nor[0], nor[1], nor[2], 0],
    }
}

fn create_cube() -> (Vec<Vertex>, Vec<u16>) {
    let vertex_data = [
        // top (0, 0, 1)
        vertex([-1, -1, 1], [0, 0, 1]),
        vertex([1, -1, 1], [0, 0, 1]),
        vertex([1, 1, 1], [0, 0, 1]),
  
    
fn create_cube() -> (Vec<Vertex>, Vec<u16>) {
    let vertex_data = [
        // top (0, 0, 1)
        vertex([-1, -1, 1], [0, 0, 1]),
        vertex([1, -1, 1], [0, 0, 1]),
        vertex([1, 1, 1], [0, 0, 1]),
        vertex([-1, 1, 1], [0, 0, 1]),
        // bottom (0, 0, -1)
        vertex([-1, 1, -1], [0, 0, -1]),
        vertex([1, 1, -1], [0, 0, -1]),
        vertex([1, -1, -1], [0, 0, -1]),
        vertex([-1, -1, -1], [0, 0, -1]),
        // right (1, 0, 0)
        vertex([1, -1, -1], [1, 0, 0]),
        vertex([1, 1, -1], [1, 0, 0]),
        vertex([1, 1, 1], [1, 0, 0]),
        vertex([1, -1, 1], [1, 0, 0]),
        // left (-1, 0, 0)
        vertex([-1, -1, 1], [-1, 0, 0]),
        vertex([-1, 1, 1], [-1, 0, 0]),
        vertex([-1, 1, -1], [-1, 0, 0]),
        vertex([-1, -1, -1], [-1, 0, 0]),
        // front (0, 1, 0)
        vertex([1, 1, -1], [0, 1, 0]),
        vertex([-1, 1, -1], [0, 1, 0]),
        vertex([-1, 1, 1], [0, 1, 0]),
        vertex([1, 1, 1], [0, 1, 0]),
        // back (0, -1, 0)
        vertex([1, -1, 1], [0, -1, 0]),
        vertex([-1, -1, 1], [0, -1, 0]),
        vertex([-1, -1, -1], [0, -1, 0]),
        vertex([1, -1, -1], [0, -1, 0]),
    ];

    let index_data: &[u16] = &[
        0, 1, 2, 2, 3, 0, // top
        4, 5, 6, 6, 7, 4, // bottom
        8, 9, 10, 10, 11, 8, // right
        12, 13, 14, 14, 15, 12, // left
        16, 17, 18, 18, 19, 16, // front
        20, 21, 22, 22, 23, 20, // back
    ];

    (vertex_data.to_vec(), index_data.to_vec())
}