fix old clippy warnings

src/flow/binary.rs

@@ -83,7 +83,7 @@ pub trait BinaryTreesMutable<'a>: BinaryTreesEmpty<'a> + BinaryTreesTreeOf<'a> {
                 Self::bind(ft, move |t| ctx.join_key_tree(tll, kl, t))
             };
             let ft = {
-                let ctx = self.clone();
+                let ctx = self;
                 Self::bind(ft, move |t| ctx.join_key_tree(t, kr, trr))
             };
             ft
@@ -123,7 +123,7 @@ pub trait BinaryTreesMutable<'a>: BinaryTreesEmpty<'a> + BinaryTreesTreeOf<'a> {
     }
 
     fn remove(self, tree: Self::Tree, key: Self::Key) -> BTWrap<'a, Self, Self::Tree> {
-        Self::bind(self.clone().split_key(tree, key.clone()), |(tl, tr)| {
+        Self::bind(self.clone().split_key(tree, key), |(tl, tr)| {
             self.join(tl, tr)
         })
     }