docs: def assign(self, value, termenc):
          """
          >>> scanner = DefaultScanner()
          >>> scanner.assign("01234", "ascii")
          >>> scanner._data
          u'01234'
          """
          if self._termenc != termenc:
              self._decoder = codecs.getincrementaldecoder(termenc)(errors='replace')
              self._termenc = termenc
          self._data = self._decoder.decode(value)