modules3 solution

solutions/10_modules/modules3.rs

@@ -1 +1,8 @@
-// Solutions will be available before the stable release. Thank you for testing the beta version 🥰
+use std::time::{SystemTime, UNIX_EPOCH};
+
+fn main() {
+    match SystemTime::now().duration_since(UNIX_EPOCH) {
+        Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
+        Err(_) => panic!("SystemTime before UNIX EPOCH!"),
+    }
+}