return [ [ 8, 8, 7, 3 ], [ 9, 9, 5, 6 ], [ 1, 9, 6, 4 ], [ 8, 3, 6, 5 ], 
  [ 7, 4, 6, 2 ], [ 2, 5, 4, 3 ], [ 1, 8, 5, 9 ], [ 1, 1, 4, 7 ], 
  [ 2, 2, 3, 7 ] ];
