1 files changed, 9 insertions, 0 deletions
diff --git a/lib/internal/onlyOnce.js b/lib/internal/onlyOnce.js
new file mode 100644
index 0000000..f4241c8
--- /dev/null
+++ b/lib/internal/onlyOnce.js
@@ -0,0 +1,9 @@
+'use strict';
+
+export default function onlyOnce(fn) {
+    return function() {
+        if (fn === null) throw new Error("Callback was already called.");
+        fn.apply(this, arguments);
+        fn = null;
+    };
+}