// Cells and their vertices.
#0={0}
#1={1,2,3}

// Induced graph on cells.
#0:.
#1:->#0.

// Individual cells.
// cell #0:
0[0]: {}

// cell #1:
0[1]: {2} --> 1,2
1[2]: {1} --> 0
2[3]: {1} --> 0