Return the sparse matrix representation of the condensation digraph
        in lil format.

def _condensation_lil(self):
        """
        Return the sparse matrix representation of the condensation digraph
        in lil format.

        """
        condensation_lil = sparse.lil_matrix(
            (self.num_strongly_connected_components,
             self.num_strongly_connected_components), dtype=bool
        )

        scc_proj = self.scc_proj
        for node_from, node_to in _csr_matrix_indices(self.csgraph):
            scc_from, scc_to = scc_proj[node_from], scc_proj[node_to]
            if scc_from != scc_to:
                condensation_lil[scc_from, scc_to] = True

        return condensation_lil