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/boids
    
    the code of the file until where you have to start completion: // Flocking boids example with gpu compute update pass
// adapted from https://github.com/austinEng/webgpu-samples/blob/master/src/examples/computeBoids.ts

use nanorand::{Rng, WyRand};
use std::{borrow::Cow, mem};
use wgpu::util::DeviceExt;

// number of boid particles to simulate

const NUM_PARTICLES: u32 = 1500;

// number of single-particle calculations (invocations) in each gpu work group

const PARTICLES_PER_GROUP: u32 = 64;

/// Example struct holds references to wgpu resources and frame persistent data
struct Example {
    particle_bind_groups: Vec<wgpu::BindGroup>,
    particle_buffers: Vec<wgpu::Buffer>,
    vertices_buffer: wgpu::Buffer,
    compute_pipeline: wgpu::ComputePipeline,
    render_pipeline: wgpu::RenderPipeline,
    work_group_count: u32,
    frame_num: usize,
}

impl crate::framework::Example for Example {
    fn required_limits() -> wgpu::Limits {
        wgpu::Limits::downlevel_defaults()
    }

    fn required_downlevel_ca
    
    fn render(&mut self, view: &wgpu::TextureView, device: &wgpu::Device, queue: &wgpu::Queue) {
        // create render pass descriptor and its color attachments
        let color_attachments = [Some(wgpu::RenderPassColorAttachment {
            view,
            resolve_target: None,
            ops: wgpu::Operations {
                // Not clearing here in order to test wgpu's zero texture initialization on a surface texture.
                // Users should avoid loading uninitialized memory since this can cause additional overhead.
                load: wgpu::LoadOp::Load,
                store: wgpu::StoreOp::Store,
            },
        })];
        let render_pass_descriptor = wgpu::RenderPassDescriptor {
            label: None,
            color_attachments: &color_attachments,
            depth_stencil_attachment: None,
            timestamp_writes: None,
            occlusion_query_set: None,
        };

        // get command encoder
        let mut command_encoder =
            device.create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });

        command_encoder.push_debug_group("compute boid movement");
        {
            // compute pass
            let mut cpass = command_encoder.begin_compute_pass(&wgpu::ComputePassDescriptor {
                label: None,
                timestamp_writes: None,
            });
            cpass.set_pipeline(&self.compute_pipeline);
            cpass.set_bind_group(0, &self.particle_bind_groups[self.frame_num % 2], &[]);
            cpass.dispatch_workgroups(self.work_group_count, 1, 1);
        }
        command_encoder.pop_debug_group();

        command_encoder.push_debug_group("render boids");
        {
            // render pass
            let mut rpass = command_encoder.begin_render_pass(&render_pass_descriptor);
            rpass.set_pipeline(&self.render_pipeline);
            // render dst particles
            rpass.set_vertex_buffer(0, self.particle_buffers[(self.frame_num + 1) % 2].slice(..));
            // the three instance-local vertices
            rpass.set_vertex_buffer(1, self.vertices_buffer.slice(..));
            rpass.draw(0..3, 0..NUM_PARTICLES);
        }
        command_encoder.pop_debug_group();

        // update frame count
        self.frame_num += 1;

        // done
        queue.submit(Some(command_encoder.finish()));
    }