Apply more suggestions.

src/context/list.rs

@@ -64,7 +64,7 @@ impl<'a, T> Iterator for IterList<'a, T> {
 
     fn next(&mut self) -> Option<Self::Item> {
         let ret = self.next;
-        self.next = self.next.map(|this| this.get_parent()).flatten();
+        self.next = self.next.and_then(|link| link.get_parent());
         ret
     }
 }