finished ch10

Generic Types Traits and Lifetimes.md

@@ -18,4 +18,33 @@ This chapter covers 3 things
 1. [Reducing Code duplication](Reducing_Code_Duplication.md)
 1. [Generics](Generics.md)
 1. [Traits](Traits.md)
-1. [Lifetimes](Lifetimes.md)
+2. [Lifetimes](Lifetimes.md)
+
+## Generic Type Parameters, Trait Bounds, and Lifetimes Together
+Here is an example with all of them together
+```rust
+use std::fmt::Display;
+
+fn longest_with_an_announcement<'a, T>(
+    x: &'a str,
+    y: &'a str,
+    ann: T,
+) -> &'a str
+where
+    T: Display,
+{
+    println!("Announcement! {ann}");
+    if x.len() > y.len() {
+        x
+    } else {
+        y
+    }
+}
+```
+This is the `longest` function that returns the longer of the two string slices.
+
+Now it has a parameter called `ann` of the generic type `T` which can only be any type that implements the `Display` trait as specified by the `where` clause
+
+The `ann` parameter will be printed using `{}`, which is why the `Display` trait is necessary
+
+Because lifetimes are a type of generic the declarations of the lifetime parameter `'a` and the generic type parameter `T` go in the same list inside the angle brackets after the function name