1 files changed, 11 insertions, 0 deletions
diff --git a/third_party/rust/headers/src/util/iter.rs b/third_party/rust/headers/src/util/iter.rs
new file mode 100644
index 0000000000..03ed691ed6
--- /dev/null
+++ b/third_party/rust/headers/src/util/iter.rs
@@ -0,0 +1,11 @@
+pub trait IterExt: Iterator {
+    fn just_one(&mut self) -> Option<Self::Item> {
+        let one = self.next()?;
+        match self.next() {
+            Some(_) => None,
+            None => Some(one),
+        }
+    }
+}
+
+impl<T: Iterator> IterExt for T {}