def __getitem__(self, li_lj_tuple):
        (li, lj) = li_lj_tuple
        i = self._indices[li]
        j = self._indices[lj]
        return self._confusion[i][j]
:return: The number of times that value ``li`` was expected and
dataset/ETHPy150Open nltk/nltk/nltk/metrics/confusionmatrix.py/ConfusionMatrix.__getitem__