When one does `from fontTools.misc.py23 import *`, everything seems to work fine.
However, linters will complain when one uses the asterisk to import all names from a module, since they can't detect when names are left undefined -- asterisks are greedy and will eat all names.
If one avoids the asterik and attempts to import explicitly, like in `from fontTools.misc.py23 import basestring`, the problem then is that, if `py23` does not re-define the name -- e.g. under python2 `basestring` or `unicode` are built-ins -- then the import statement raises `ImportError`.
The same happens for the `unichr` function on a "wide" Python 2 build (in which `sys.maxunicode == 0x10FFFF`).
Now, to work around this, we need to re-assign those built-ins to their very same names. This may look silly, but at least it works.
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