diff --git a/lib/xmet/util.py b/lib/xmet/util.py
index f6ccf12..d16372a 100644
--- a/lib/xmet/util.py
+++ b/lib/xmet/util.py
@@ -29,3 +29,11 @@ def each_chunk(fh: io.TextIOBase, sep: str, strip=None):
 
                 if ret != '':
                     yield ret
+
+def cmp(a, b):
+    if a == b:
+        return 0
+    elif a > b:
+        return -1
+    elif a < b:
+        return 1