def retrieve_word(j_, reverse_lookup, indices, tokens):
    """
    Input:  j_ = int (overall word index),
            reverse_lookup, indices, tokens (all three are previous outputs )
    Output: (i,j,token) triple, i = the sentence index, the original word index j, and the actual token (string).
    """
    #example: j_ = 30 #overall_index. now what is the original word?
    i,i_ = reverse_lookup[j_]
    j = indices[i][i_]
    return i, j, tokens[i][j]