Updated src/generic_types_traits_and_lifetimes/traits.md'.

projects/trait_demo/src/main.rs

@@ -1,5 +1,20 @@
 use aggregator::{SocialPost, Summary, NewsArticle};
 
+pub fn notify(item: &impl Summary) {
+    println! ("突发新闻！{}", item.summarize());
+}
+
+fn return_summarizable() -> impl Summary {
+    SocialPost {
+        username: String::from("horse_ebooks"),
+        content: String::from(
+            "当然，正如咱们或许已经知道的一样，朋友们"
+        ),
+        reply: false,
+        retweet: false,
+    }
+}
+
 fn main() {
     let post = SocialPost {
         username: String::from("horse_ebooks"),