Index: Modules/gdbmmodule.c
===================================================================
--- Modules/gdbmmodule.c	(révision 60983)
+++ Modules/gdbmmodule.c	(copie de travail)
@@ -178,6 +178,33 @@
     return 0;
 }
 
+static int
+dbm_contains(register dbmobject *dp, PyObject *v)
+{
+    datum key;
+
+    if (PyString_AsStringAndSize(v, &key.dptr, &key.dsize)) {
+        return -1;
+    }
+
+    check_dbmobject_open(dp);
+    
+    return gdbm_exists(dp->di_dbm, key);
+}
+
+static PySequenceMethods dbm_as_sequence = {
+    (lenfunc)dbm_length,               /*_length*/
+       0,              /*sq_concat*/
+       0,                      /*sq_repeat*/
+       0,                      /*sq_item*/
+       0,                      /*sq_slice*/
+       0,                      /*sq_ass_item*/
+       0,                  /*sq_ass_slice*/
+       (objobjproc)dbm_contains,               /*sq_contains*/
+       0,                  /*sq_inplace_concat*/
+       0                   /*sq_inplace_repeat*/
+};
+
 static PyMappingMethods dbm_as_mapping = {
     (lenfunc)dbm_length,		/*mp_length*/
     (binaryfunc)dbm_subscript,          /*mp_subscript*/
@@ -381,7 +408,7 @@
     0,                                  /*tp_compare*/
     0,                                  /*tp_repr*/
     0,                                  /*tp_as_number*/
-    0,                                  /*tp_as_sequence*/
+    &dbm_as_sequence,                   /*tp_as_sequence*/
     &dbm_as_mapping,                    /*tp_as_mapping*/
     0,                                  /*tp_hash*/
     0,                                  /*tp_call*/
@@ -389,7 +416,7 @@
     0,                                  /*tp_getattro*/
     0,                                  /*tp_setattro*/
     0,                                  /*tp_as_buffer*/
-    0,                                  /*tp_xxx4*/
+    Py_TPFLAGS_DEFAULT,                 /*tp_xxx4*/
     gdbm_object__doc__,                 /*tp_doc*/
 };