The part of the code where that is more likely to happen is the push() method.One might also submit a producer (push_with_producer()) erroneously returning strings on more() though; how to properly fix this one is not clear to me because of the bad asynchat design. I'd be for simply raising an exception in push() as in:diff --git a/Lib/asynchat.py b/Lib/asynchat.py--- a/Lib/asynchat.py+++ b/Lib/asynchat.py@@ -181,6 +181,8 @@         self.close()      def push (self, data):+        if not isinstance(data, bytes):+            raise TypeError("data must be a bytes object")         sabs = self.ac_out_buffer_size         if len(data) > sabs:             for i in range(0, len(data), sabs):