diff --git a/src/flow/binary/bounds/bound.rs b/src/flow/binary/bounds/bound.rs
index a92fdbf..7fc5620 100644
--- a/src/flow/binary/bounds/bound.rs
+++ b/src/flow/binary/bounds/bound.rs
@@ -1,3 +1,4 @@
+use crate::flow::binary::avl::*;
 use crate::flow::binary::*;
 use crate::func::context::*;
 
@@ -9,6 +10,14 @@ pub struct Bound<A, T> {
     bounds: Bounds<A>,
 }
 
+impl<A, T> std::ops::Deref for Bound<A, T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.bound
+    }
+}
+
 pub struct BoundNode2<A, T> {
     boundsl: Bounds<A>,
     boundsr: Bounds<A>,
@@ -19,11 +28,17 @@ pub struct BoundNode2<A, T> {
 #[derive(Clone)]
 pub struct BoundTrees<BT>(BT);
 
+impl<BT> BoundTrees<BT> {
+    pub fn new(bt: BT) -> Self {
+        Self(bt)
+    }
+}
+
 impl<'a, BT: FunctorContext<'a>> FunctorContext<'a> for BoundTrees<BT> {
     type T = BT::T;
 }
 
-trait BinaryTreesBindable<'a>: BinaryTrees<'a> {
+pub trait BinaryTreesBindable<'a>: BinaryTrees<'a> {
     fn bounds_error<T: 'a>(&self, error: BoundsError<Self::Key>) -> BTWrap<'a, Self, T>;
 
     fn bounds_bind<A: 'a, B: 'a>(
@@ -185,3 +200,22 @@ impl<'a, BT: BinaryTreesBindable<'a> + BinaryTreesTryJoin<'a>> BinaryTreesTryJoi
         )
     }
 }
+
+impl<
+        'a,
+        BT: BinaryTreesBindable<'a>
+            + BinaryTreesTreeOf<'a>
+            + BinaryTreesEmpty<'a>
+            + BinaryTreesHeight<'a>
+            + BinaryTreesTryJoin<'a>,
+    > BinaryTreesMutable<'a> for BoundTrees<BT>
+{
+    fn join_key(
+        self,
+        tl: Self::Tree,
+        key: Self::Key,
+        tr: Self::Tree,
+    ) -> BTWrap<'a, Self, Self::Node> {
+        self.join_key_balanced(tl, key, tr)
+    }
+}
diff --git a/src/mrds/trees/avl.rs b/src/mrds/trees/avl.rs
index f1d017a..90fc8f3 100644
--- a/src/mrds/trees/avl.rs
+++ b/src/mrds/trees/avl.rs
@@ -1,7 +1,7 @@
 use std::{fmt::Display, marker::PhantomData, rc::Rc};
 
 use crate::flow::{
-    binary::{avl::*, *},
+    binary::{avl::*, bounds::bound::BinaryTreesBindable, *},
     comparator::*,
 };
 use crate::func::{context::*, *};
@@ -197,8 +197,16 @@ impl<'a, A: 'a + PartialOrd + Clone> BinaryTreesTryJoin<'a> for AvlTs<A> {
     }
 }
 
+impl<'a, A: 'a + PartialOrd + Clone> BinaryTreesBindable<'a> for AvlTs<A> {
+    fn bounds_error<T: 'a>(&self, _error: bounds::BoundsError<Self::Key>) -> BTWrap<'a, Self, T> {
+        panic!("bounds violated");
+    }
+}
+
 #[cfg(test)]
 mod tests {
+    use crate::flow::binary::bounds::bound::*;
+
     use super::*;
 
     #[test]
@@ -221,4 +229,25 @@ mod tests {
         }
         // assert!(false);
     }
+
+    #[test]
+    fn test_with_bounds() {
+        let trees = BoundTrees::new(AvlTs::new());
+        let mut tree = trees.empty();
+        for i in [
+            8, 3, 10, 17, 0, 13, 6, 1, 11, 5, 4, 7, 18, 14, 15, 9, 2, 19, 16, 12,
+        ] {
+            tree = trees.clone().add_tree(tree, i);
+            assert!(tree.balanced());
+            // println!("{} {}", tree.height, tree);
+        }
+        for i in [
+            2, 9, 4, 7, 8, 10, 17, 1, 13, 15, 18, 12, 5, 0, 3, 6, 16, 19, 14, 11,
+        ] {
+            tree = trees.clone().remove(tree, i);
+            assert!(tree.balanced());
+            // println!("{} {}", tree.height, tree);
+        }
+        // assert!(false);
+    }
 }