flatten(): Renamed from __call__() which is (silently) deprecated. __call__() can be 2-3x slower than the equivalent normal method.
flatten(): Renamed from __call__() which is (silently) deprecated.
__call__() can be 2-3x slower than the equivalent normal method.

_handle_message(): The structure of message/rfc822 message has
changed.  Now parent's payload is a list of length 1, and the zeroth
element is the Message sub-object.  Adjust the printing of such
message trees to reflect this change.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator