diff --git a/corpora/tries.py b/corpora/tries.py
new file mode 100644
index 0000000..1df214a
--- /dev/null
+++ b/corpora/tries.py
@@ -0,0 +1,7 @@
+def f1(a):
+    try:
+        return int(a)
+    except:
+        return None
+
+corpus = [f1]