Problem:    Python 3: vim.error is a 'str' instead of an 'Exception' object,
            so 'except' or 'raise' it causes a 'SystemError' exception.
            Buffer objects do not support slice assignment.
            When exchanging text between Vim and Python, multibyte texts become
            gabage or cause Unicode Expceptions, etc.
            'py3file' tries to read in the file as Unicode, sometimes causes
            UnicodeDecodeException
Solution:   Fix the problems. (lilydjwg)