/// ```
/// use std::collections::HashMap;
///
-/// // type inference lets us omit an explicit type signature (which
-/// // would be `HashMap<&str, &str>` in this example).
+/// // Type inference lets us omit an explicit type signature (which
+/// // would be `HashMap<String, String>` in this example).
/// let mut book_reviews = HashMap::new();
///
-/// // review some books.
-/// book_reviews.insert("Adventures of Huckleberry Finn", "My favorite book.");
-/// book_reviews.insert("Grimms' Fairy Tales", "Masterpiece.");
-/// book_reviews.insert("Pride and Prejudice", "Very enjoyable.");
-/// book_reviews.insert("The Adventures of Sherlock Holmes", "Eye lyked it alot.");
+/// // Review some books.
+/// book_reviews.insert(
+/// "Adventures of Huckleberry Finn".to_string(),
+/// "My favorite book.".to_string(),
+/// );
+/// book_reviews.insert(
+/// "Grimms' Fairy Tales".to_string(),
+/// "Masterpiece.".to_string(),
+/// );
+/// book_reviews.insert(
+/// "Pride and Prejudice".to_string(),
+/// "Very enjoyable.".to_string(),
+/// );
+/// book_reviews.insert(
+/// "The Adventures of Sherlock Holmes".to_string(),
+/// "Eye lyked it alot.".to_string(),
+/// );
///
-/// // check for a specific one.
+/// // Check for a specific one.
+/// // When collections store owned values (String), they can still be
+/// // queried using references (&str).
/// if !book_reviews.contains_key("Les Misérables") {
/// println!("We've got {} reviews, but Les Misérables ain't one.",
/// book_reviews.len());
/// // oops, this review has a lot of spelling mistakes, let's delete it.
/// book_reviews.remove("The Adventures of Sherlock Holmes");
///
-/// // look up the values associated with some keys.
+/// // Look up the values associated with some keys.
/// let to_find = ["Pride and Prejudice", "Alice's Adventure in Wonderland"];
-/// for book in &to_find {
+/// for &book in &to_find {
/// match book_reviews.get(book) {
/// Some(review) => println!("{}: {}", book, review),
/// None => println!("{} is unreviewed.", book)
/// }
/// }
///
-/// // iterate over everything.
+/// // Iterate over everything.
/// for (book, review) in &book_reviews {
/// println!("{}: \"{}\"", book, review);
/// }
/// ```
/// use std::collections::HashSet;
/// // Type inference lets us omit an explicit type signature (which
-/// // would be `HashSet<&str>` in this example).
+/// // would be `HashSet<String>` in this example).
/// let mut books = HashSet::new();
///
/// // Add some books.
-/// books.insert("A Dance With Dragons");
-/// books.insert("To Kill a Mockingbird");
-/// books.insert("The Odyssey");
-/// books.insert("The Great Gatsby");
+/// books.insert("A Dance With Dragons".to_string());
+/// books.insert("To Kill a Mockingbird".to_string());
+/// books.insert("The Odyssey".to_string());
+/// books.insert("The Great Gatsby".to_string());
///
/// // Check for a specific one.
/// if !books.contains("The Winds of Winter") {
/// ```
/// use std::collections::HashSet;
/// #[derive(Hash, Eq, PartialEq, Debug)]
-/// struct Viking<'a> {
-/// name: &'a str,
+/// struct Viking {
+/// name: String,
/// power: usize,
/// }
///
/// let mut vikings = HashSet::new();
///
-/// vikings.insert(Viking { name: "Einar", power: 9 });
-/// vikings.insert(Viking { name: "Einar", power: 9 });
-/// vikings.insert(Viking { name: "Olaf", power: 4 });
-/// vikings.insert(Viking { name: "Harald", power: 8 });
+/// vikings.insert(Viking { name: "Einar".to_string(), power: 9 });
+/// vikings.insert(Viking { name: "Einar".to_string(), power: 9 });
+/// vikings.insert(Viking { name: "Olaf".to_string(), power: 4 });
+/// vikings.insert(Viking { name: "Harald".to_string(), power: 8 });
///
/// // Use derived implementation to print the vikings.
/// for x in &vikings {
/// use std::collections::HashSet;
///
/// fn main() {
-/// let viking_names: HashSet<&str> =
+/// let viking_names: HashSet<&'static str> =
/// [ "Einar", "Olaf", "Harald" ].iter().cloned().collect();
/// // use the values stored in the set
/// }