ACCEPTS: string or anything printable with "%s" conversion.
if s is not None:
self._label = "%s" % (s, )
else:
self._label = None
self.pchanged()
self.stale = True
After Change
ACCEPTS: object
if s is not None:
self._label = six.text_type(s)
else:
self._label = None
self.pchanged()
self.stale = True