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: codec_benchmarks.rs
    path of file: ./repos/OctoBase/libs/jwst-codec-utils/benches
    
    the code of the file until where you have to start completion: use criterion::{criterion_group, criterion_main, Criterion, SamplingMode};
use lib0::{
    decoding::{Cursor, Read},
    encoding::Write,
};

const BENCHMARK_SIZE: u32 = 100000;

fn codec(c: &mut Criterion) {
    let mut codec_group = c.benchmark_group("codec");
    codec_group.sampling_mode(SamplingMode::Flat);
    {
        codec_group.bench_function("lib0 encode var_int (64 bit)", |b| {
            b.iter(|| {
                let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8);
                for i in 0..(BENCHMARK_SIZE as i64) {
                    encoder.write_var(i);
                }
            })
        });
        codec_group.bench_function("lib0 decode var_int (64 bit)", |b| {
            let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8);
            for i in 0..(BENCHMARK_SIZE as i64) {
                encoder.write_var(i);
            }

            b.iter(|| {
                let mut decoder = Cursor::from(&encoder);
                for i in 0..(BENCHMARK_SIZE as i64) {
                    let num: i64 = decoder.read_var().unwrap();
                    assert_eq!(num, i);
                }
            })
        });
    }

    {
        codec_group.bench_function("lib0 encode var_uint (32 bit)", |b| {
            b.iter(|| {
                let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8);
                for i in 0..BENCHMARK_SIZE {
                    encoder.write_var(i);
                }
            })
        });
        codec_group.bench_function("lib0 decode var_uint (32 bit)", |b| {
            let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8
    
fn codec(c: &mut Criterion) {
    let mut codec_group = c.benchmark_group("codec");
    codec_group.sampling_mode(SamplingMode::Flat);
    {
        codec_group.bench_function("lib0 encode var_int (64 bit)", |b| {
            b.iter(|| {
                let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8);
                for i in 0..(BENCHMARK_SIZE as i64) {
                    encoder.write_var(i);
                }
            })
        });
        codec_group.bench_function("lib0 decode var_int (64 bit)", |b| {
            let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8);
            for i in 0..(BENCHMARK_SIZE as i64) {
                encoder.write_var(i);
            }

            b.iter(|| {
                let mut decoder = Cursor::from(&encoder);
                for i in 0..(BENCHMARK_SIZE as i64) {
                    let num: i64 = decoder.read_var().unwrap();
                    assert_eq!(num, i);
                }
            })
        });
    }

    {
        codec_group.bench_function("lib0 encode var_uint (32 bit)", |b| {
            b.iter(|| {
                let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8);
                for i in 0..BENCHMARK_SIZE {
                    encoder.write_var(i);
                }
            })
        });
        codec_group.bench_function("lib0 decode var_uint (32 bit)", |b| {
            let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8);
            for i in 0..BENCHMARK_SIZE {
                encoder.write_var(i);
            }

            b.iter(|| {
                let mut decoder = Cursor::from(&encoder);
                for i in 0..BENCHMARK_SIZE {
                    let num: u32 = decoder.read_var().unwrap();
                    assert_eq!(num, i);
                }
            })
        });
    }

    {
        codec_group.bench_function("lib0 encode var_uint (64 bit)", |b| {
            b.iter(|| {
                let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8);
                for i in 0..(BENCHMARK_SIZE as u64) {
                    encoder.write_var(i);
                }
            })
        });
        codec_group.bench_function("lib0 decode var_uint (64 bit)", |b| {
            let mut encoder = Vec::with_capacity(BENCHMARK_SIZE as usize * 8);
            for i in 0..(BENCHMARK_SIZE as u64) {
                encoder.write_var(i);
            }

            b.iter(|| {
                let mut decoder = Cursor::from(&encoder);
                for i in 0..(BENCHMARK_SIZE as u64) {
                    let num: u64 = decoder.read_var().unwrap();
                    assert_eq!(num, i);
                }
            })
        });
    }
}