a simple function written in rust

hello_rust.rs

pub fn main(name: &str) -> String {
  let mut ret_val = String::from("xin chào, ");
  ret_val.push_str(name);
  println!("{}", ret_val);
  ret_val
}

// normally `main` isn't supposed to return `String` type
// but this is done on purpose here to support a specially intended use case