add `--version` CLI flag

src/lib.rs

@@ -1,6 +1,17 @@
 use rand::{seq::IndexedRandom as _, Rng as _};
 
-pub fn main() {
+pub fn main() -> Result<(), String> {
+    let mut args = std::env::args();
+    let _ = args.next();
+    match args.next().as_deref() {
+        None => {}
+        Some("--version") => {
+            println!("{} {}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION"));
+            return Ok(());
+        }
+        Some(_) => return Err("Unknown CLI arg".to_string()),
+    }
+
     println!("{}", create_passphrase(" ", 8));
     println!("{}", create_pin(9));
     println!("{}", create_base32(8));
@@ -8,6 +19,7 @@ pub fn main() {
     println!("Press Enter");
     let mut input = String::new();
     std::io::stdin().read_line(&mut input).ok();
+    Ok(())
 }
 
 /// Generates a Base32 string per RFC 4648, Section 6.

src/main.rs

@@ -1,3 +1,3 @@
-fn main() {
+fn main() -> Result<(), String> {
     division_of_one::main()
 }