finshed ch17.1

hello-async/src/main.rs

@@ -0,0 +1,21 @@
+extern crate trpl;
+use trpl::Html;
+
+async fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    let url = &args[1];
+    match page_title(url).await {
+        Some(title) => println!("The title for {url} was {title}"),
+        None => println!("{url} had no title"),
+    }
+}
+
+async fn page_title(url: &str) -> Option<String> {
+    let res = trpl::get(url).await;
+
+    let res_text = res.text().await;
+
+    Html::parse(&res_text)
+        .select_first("title")
+        .map(|title_element| title_element.inner_html())
+}