'Return an open file pointer for the data file for the given
part of speech.'

def _data_file(self, pos):

    if (pos == ADJ_SAT):
        pos = ADJ
    if (self._data_file_map.get(pos) is None):
        fileid = (u'data.%s' % self._FILEMAP[pos])
        self._data_file_map[pos] = self.open(fileid)
    return self._data_file_map[pos]
