Add Pickler.clear_memo() so the pickle and cPickle modules are more similar.
diff --git a/Lib/pickle.py b/Lib/pickle.py
index 541624a..5837884 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -115,6 +115,9 @@
         self.memo = {}
         self.bin = bin
 
+    def clear_memo(self):
+        self.memo.clear()
+
     def dump(self, object):
         self.save(object)
         self.write(STOP)