1No `main` function was found in a binary crate.23To fix this error, add a `main` function:45```6fn main() {7    // Your program will start here.8    println!("Hello world!");9}10```1112If you don't know the basics of Rust, you can look at the13[Rust Book][rust-book] to get started.1415[rust-book]: https://doc.rust-lang.org/book/