{
  0: ( 1 2 )
  1: ( 0 3 4 )
  2: ( 0 3 5 )
  3: ( 4 5 )
  4: ( 1 3 6 )
  5: ( 2 3 6 )
  6: ( 2 3 4 )
  7: ( 1 3 5 )
  8: ( 0 3 6 )
}