diff -r 478c23ce7cef -r 20fa28637737 src/bisection_tree/btfn.rs
--- a/src/bisection_tree/btfn.rs	Wed Sep 03 12:55:27 2025 -0500
+++ b/src/bisection_tree/btfn.rs	Wed Sep 03 13:15:32 2025 -0500
@@ -58,6 +58,13 @@
     {
         MyCow::Owned(self)
     }
+
+    fn ref_cow_owned<'b>(&'b self) -> MyCow<'b, Self::OwnedVariant>
+    where
+        Self: 'b,
+    {
+        MyCow::Borrowed(self)
+    }
 }
 
 impl<F: Float, G, BT, const N: usize> Space for BTFN<F, G, BT, N>