use unwrap_or to get default value

src/main.rs

@@ -1,5 +1,14 @@
+fn add_10(value: Option<u32>) -> Result<u32, String> {
+    match value {
+        Some(v) => Ok(v + 10),
+        None => Err(String::from("value was empty")),
+    }
+}
+
 fn main() {
-    for value in (-10..10).rev() {
-        println!("Value: {}", value);
-    }
+    let value = add_10(None);
+
+    println!("Result is: {}", value.unwrap_or(42));
+
+    panic!("Non recoverable error.");
 }