Map::keys and Map::values can be used method-call style.

src/stdlib.rs

@@ -16,7 +16,7 @@ mod inner {
     pub use core_error as error;
 
     pub mod collections {
-        pub use hashbrown::{HashMap, HashSet};
+        pub use hashbrown::{hash_map, hash_set, HashMap, HashSet};
     }
 }