1 files changed, 12 insertions, 3 deletions
diff --git a/README.md b/README.md
index e0ec639..2af017b 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,9 @@
 # collect-once-hashmap
 
-This crate provides a type `CollectOnceHashMap` that can be collected from an
-iterator just like a normal `std::collections::HashMap`, but it makes sure that
-a duplicated key results in an error.
+This crate provides a type `CollectOnceHashMap` (and the same for `BTreeMap`
+that can be collected from an iterator just like a normal
+`std::collections::HashMap`, but it makes sure that a duplicated key results in
+an error.
 
 Example:
 
@@ -15,6 +16,14 @@ let hm = vec![(1, 1), (1, 2)]
 
 assert!(hm.is_err());
 assert!(std::matches!(hm, Err(Error::DuplicatedKey(1))));
+
+let bm = vec![(1, 1), (1, 2)]
+    .into_iter()
+    .collect::<CollectOnceBTreeMap<u8, u8>>()
+    .into_inner();
+
+assert!(bm.is_err());
+assert!(std::matches!(bm, Err(Error::DuplicatedKey(1))));
 ```