diff --git a/src/rstd/collections/tree.rs b/src/rstd/collections/tree.rs
index 7b86a99..ad18226 100644
--- a/src/rstd/collections/tree.rs
+++ b/src/rstd/collections/tree.rs
@@ -237,15 +237,23 @@ mod tests {
     use std::convert::Infallible;
 
     use crate::{
-        flow::{binary::*, comparator::*},
+        flow::{
+            binary::{balancing::*, *},
+            comparator::*,
+        },
         rstd::atomic_object::*,
         testing::TestContextPlain,
     };
 
     use super::context::*;
 
-    type Trees =
-        TreeContext2<'static, TestContextPlain, AtomicObject<u64>, DefaultComparator, Infallible>;
+    type Trees = TreeContext2<
+        'static,
+        TestContextPlain,
+        AtomicObject<u64>,
+        DefaultComparator,
+        WrappedExtra<BalancingError, Infallible>,
+    >;
 
     fn new_trees() -> Trees {
         Trees::new((DefaultComparator.into(), u64::f()))
@@ -256,4 +264,12 @@ mod tests {
         let trees = new_trees();
         assert_eq!(trees.height(&trees.empty()), 0);
     }
+
+    #[test]
+    fn one_has_height_1() {
+        let trees = BalancedTrees::new(new_trees());
+        let tree = trees.empty();
+        let tree = trees.clone().add_tree(tree, 0.into()).unwrap();
+        assert_eq!(trees.height(&tree), 1);
+    }
 }
diff --git a/src/rstd/collections/tree/context.rs b/src/rstd/collections/tree/context.rs
index 1d66f6e..6578dd6 100644
--- a/src/rstd/collections/tree/context.rs
+++ b/src/rstd/collections/tree/context.rs
@@ -26,32 +26,32 @@ impl<Cl: Clone, T> Clone for TreeContext<Cl, T> {
     }
 }
 
-pub enum TreeContextError<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx>, E: 'a> {
-    Resolution(ResolutionFailure<'a, Ctx, Node<'a, Ctx, A>>),
+#[derive(Debug)]
+pub enum TreeContextError<R, E> {
+    Resolution(R),
     Extra(E),
 }
 
-impl<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx>, E: 'a>
-    From<ResolutionFailure<'a, Ctx, Node<'a, Ctx, A>>> for TreeContextError<'a, Ctx, A, E>
+pub type TreeContextError2<'a, Ctx, A, E> =
+    TreeContextError<ResolutionFailure<'a, Ctx, Node<'a, Ctx, A>>, E>;
+
+impl<L, P, E> From<ResolutionError<L, TreeParseError<P>>>
+    for TreeContextError<ResolutionError<L, TreeParseError<P>>, E>
 {
-    fn from(value: ResolutionFailure<'a, Ctx, Node<'a, Ctx, A>>) -> Self {
+    fn from(value: ResolutionError<L, TreeParseError<P>>) -> Self {
         Self::Resolution(value)
     }
 }
 
-type TreeParseError2<'a, A> = TreeParseError<ParseErrorA<'a, A>>;
-
-impl<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx>, E: 'a> From<TreeParseError2<'a, A>>
-    for TreeContextError<'a, Ctx, A, E>
+impl<L, P, E> From<TreeParseError<P>>
+    for TreeContextError<ResolutionError<L, TreeParseError<P>>, E>
 {
-    fn from(value: TreeParseError2<'a, A>) -> Self {
+    fn from(value: TreeParseError<P>) -> Self {
         ResolutionError::Parse(value).into()
     }
 }
 
-impl<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx>, E: 'a> From<HeightError>
-    for TreeContextError<'a, Ctx, A, E>
-{
+impl<L, P, E> From<HeightError> for TreeContextError<ResolutionError<L, TreeParseError<P>>, E> {
     fn from(value: HeightError) -> Self {
         TreeParseError::HeightValue(value).into()
     }
@@ -67,7 +67,7 @@ impl<
         E: 'a + Send,
     > FunctorContext<'a> for TreeContext2<'a, Ctx, A, C, E>
 {
-    type T = FallibleMonad<'a, Ctx, TreeContextError<'a, Ctx, A, E>>;
+    type T = FallibleMonad<'a, Ctx, TreeContextError2<'a, Ctx, A, E>>;
 }
 
 impl<
@@ -181,6 +181,24 @@ impl<
     }
 }
 
+impl<
+        'a,
+        Ctx: Context<'a>,
+        A: Mentionable<'a, Ctx> + Clone,
+        C: 'a + Comparator<A>,
+        E: 'a + Send,
+    > BinaryTreesTryJoin<'a> for TreeContext2<'a, Ctx, A, C, E>
+{
+    fn try_join(
+        &self,
+        tl: Self::Tree,
+        key: Self::Key,
+        tr: Self::Tree,
+    ) -> BTWrap<'a, Self, Self::Node> {
+        Self::pure(Node { l: tl, r: tr, key })
+    }
+}
+
 impl<
         'a,
         Ctx: Context<'a>,
@@ -194,30 +212,25 @@ impl<
     }
 }
 
+#[derive(Debug)]
 pub enum WrappedExtra<W, E> {
     Wrapped(W),
     Extra(E),
 }
 
-impl<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx>, W: 'a, E: 'a> From<WrappedExtra<W, E>>
-    for TreeContextError<'a, Ctx, A, WrappedExtra<W, E>>
-{
+impl<R, E, W> From<WrappedExtra<W, E>> for TreeContextError<R, WrappedExtra<W, E>> {
     fn from(value: WrappedExtra<W, E>) -> Self {
         Self::Extra(value)
     }
 }
 
-impl<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx>, E: 'a> From<BalancingError>
-    for TreeContextError<'a, Ctx, A, WrappedExtra<BalancingError, E>>
-{
+impl<R, E> From<BalancingError> for TreeContextError<R, WrappedExtra<BalancingError, E>> {
     fn from(value: BalancingError) -> Self {
         WrappedExtra::Wrapped(value).into()
     }
 }
 
-impl<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx>, E: 'a> From<BoundsError<A>>
-    for TreeContextError<'a, Ctx, A, WrappedExtra<BoundsError<A>, E>>
-{
+impl<R, A, E> From<BoundsError<A>> for TreeContextError<R, WrappedExtra<BoundsError<A>, E>> {
     fn from(value: BoundsError<A>) -> Self {
         WrappedExtra::Wrapped(value).into()
     }