code: def _reset_corpus_iterator(self):
          
          self.__context = etree.iterparse(self.exportxml_file, events=('end',),
                                           tag='text', recover=True)
docs: create an iterator over all documents in the file (i.e. all
          <text> elements). The recover parameter is used, as the Tüba-D/Z 8.0
          corpus used for testing isn't completely valid XML (i.e. there are two
          element IDs used twice).
  
          Once you have iterated over all documents, call this method again
          if you want to iterate over them again.