Create a new binary project using cargo new --bin pngme. My implementation is called pngme because I think I'm clever. Feel free to name yours whatever you want.

Copy the following code into your file.

mod args;
mod chunk;
mod chunk_type;
mod commands;
mod png;

pub type Error = Box<dyn std::error::Error>;
pub type Result<T> = std::result::Result<T, Error>;

fn main() -> Result<()> {

Your project will need to match this module structure in order to for the unit tests to pass. The easiest way to set this up is to make a separate file for each module. For example, create a file called in your src folder. The code in this file will be your chunk module. See the module chapters in the book for more info.

I've provided Error and Result type aliases that will make it easy to use the ? operator in your code. My own implementation uses the anyhow crate for error handling. It's got some nice macros like bail! that make it easy to return errors in the middle of a function. If you're reading this in the future, we've all probably moved on from anyhow to some other fancy error handling crate. You do you.