diff --git a/Lib/dumbdbm.py b/Lib/dumbdbm.py
index f1cc41b..30ec114 100644
--- a/Lib/dumbdbm.py
+++ b/Lib/dumbdbm.py
@@ -135,6 +135,13 @@
     def has_key(self, key):
         return self._index.has_key(key)
 
+    def __contains__(self, key):
+        return self._index.has_key(key)
+
+    def iterkeys(self):
+        return self._index.iterkeys()
+    __iter__ = iterkeys
+
     def __len__(self):
         return len(self._index)
 
@@ -143,6 +150,6 @@
         self._datfile = self._dirfile = self._bakfile = None
 
 
-def open(file, flag = None, mode = None):
+def open(file, flag=None, mode=None):
     # flag, mode arguments are currently ignored
     return _Database(file)