Init from func return with params

rustbook/functions/src/main.rs

@@ -1,9 +1,9 @@
-fn five() -> i32 {
-    5
-}
-
 fn main() {
-    let x = five();
+    let x = plus_one(5);
 
     println!("The value of x is: {}", x);
 }
+
+fn plus_one(x: i32) -> i32 {
+    x + 1
+}