I'm not sure this is still being considered, so I just wanted to add my
opinion.  This seems like such a simple request being made overly
complicated.  We just want seconds since epoch since that is used in
many other functions and libraries (i.e. the time module,
os.stat().st_mtime).  Why is there toordinal()?!?  If there is going to
be any toxxx() methods, there should definitely be a
tosecs()/totimestamp() method or an 'epoch/timestamp' attribute.  For
boundary cases, I would look to the std time module for guidance.