added _weakref mixins

test/completion/std.py

@@ -18,3 +18,16 @@ next(re.finditer('a', 'a')).start()
 
 #? str()
 re.sub('a', 'a')
+
+# -----------------
+# ref
+# -----------------
+import weakref
+
+#? int()
+weakref.proxy(1)
+
+#? weakref.ref
+weakref.ref(1)
+#? int()
+weakref.ref(1)()