Requesting an example

Hi! Does anyone have an example of basic operation, that includes a function or struct field containing each relevant type (key, poly, nonce)? Thank you!

Here is my non-compiling attempt:

Cargo.toml:

crypto = { package = "chacha20poly1305", version = "^0.10.1", default-features = false, features = ["rand_core"] }
rand_core = "^0.6.4"
generic-array = "^1.0.0"

Program:

use chacha20poly1305::{
    aead::{AeadCore, KeyInit},
    ChaCha20Poly1305 as Poly, Nonce
};
use generic_array::GenericArray;

type Key = GenericArray<u8, 12>;
type Nonce2 = GenericArray<u8, 12>;

pub fn make_cipher(rng: &mut Rng) -> (Key, Poly, Nonce) {
    let key = Poly::generate_key(rng);
    let cipher = Poly::new(&key);

    // The nonce is unique per message. 96-bits.
    let nonce = Poly::generate_nonce(rng);

    (key, cipher, nonce)
}

pub fn encrypt(data: &mut [u8], cipher: &Poly, nonce: &Nonce) {
    let ciphertext = cipher.encrypt(&nonce, data).unwrap();
}

pub fn decrypt(data: &mut [u8], cipher: &Poly, nonce: &Nonce) {
    let ciphertext = cipher.decrypt(&nonce, data).unwrap();
}

The issue's Cargo.toml and non-compiling Rust program are the starting points; review the chacha20poly1305 usage of Key, Poly, and Nonce and determine what example should be documented. Done means a basic compiling operation example covers those types.