in file can\message.py
line 83 function init for Message
pass is_extended_id=None also extended_id=None which are all defaul.
And from meaning, it means no extended.
However line 113 in the same file
self.is_extended_id = True if extended_id is None else extended_id
this logic makes extended true as extended_id is None which is logical error.
expect should be
self.is_extended_id = True if extended_id is not

None else extended_id