Cross-validation of decision tree
 y_0:
  z_0:
   0 happens 3 times.
  z_1:
   1 happens 2 times.
 y_1:
  z_0:
   1 happens 2 times.
  z_1:
   x_1:
    1_is correct_4_times.
    0_is correct_1_times.
Training correct is: 0.9166667
Test correct is: 0
 y_0:
  z_1:
   x_0:
    0_is correct_1_times.
    1_is correct_1_times.
   x_1:
    1_is correct_1_times.
    0_is correct_1_times.
  z_0:
   0 happens 3 times.
 y_1:
  1 happens 5 times.
Training correct is: 0.8333333
Test correct is: 0.5
 x_1:
  z_0:
   1 happens 3 times.
  z_1:
   y_0:
    1_is correct_1_times.
    0_is correct_1_times.
   y_1:
    1_is correct_3_times.
    0_is correct_1_times.
 x_0:
  0 happens 3 times.
Training correct is: 0.8333333
Test correct is: 0.5
 y_0:
  z_1:
   1 happens 2 times.
  z_0:
   0 happens 3 times.
 y_1:
  z_1:
   x_1:
    0_is correct_1_times.
    1_is correct_4_times.
  z_0:
   1 happens 2 times.
Training correct is: 0.9166667
Test correct is: 0
 y_1:
  1 happens 6 times.
 y_0:
  x_0:
   z_0:
    0 happens 2 times.
   z_1:
    0_is correct_1_times.
    1_is correct_1_times.
  x_1:
   z_0:
    1 happens 1 times.
   z_1:
    0 happens 1 times.
Training correct is: 0.9166667
Test correct is: 0.25
 x_1:
  y_1:
   z_1:
    1_is correct_3_times.
    0_is correct_1_times.
   z_0:
    1 happens 2 times.
  y_0:
   z_0:
    0_is correct_1_times.
    1_is correct_1_times.
   z_1:
    1 happens 1 times.
 x_0:
  z_1:
   y_0:
    1_is correct_1_times.
    0_is correct_1_times.
  z_0:
   0 happens 1 times.
Training correct is: 0.75
Test correct is: 0
 x_0:
  0 happens 3 times.
 x_1:
  1 happens 9 times.
Training correct is: 1
Test correct is: 0
 x_1:
  y_0:
   z_0:
    1_is correct_1_times.
    0_is correct_1_times.
   z_1:
    0_is correct_1_times.
    1_is correct_1_times.
  y_1:
   z_0:
    1 happens 2 times.
   z_1:
    1_is correct_3_times.
    0_is correct_1_times.
 x_0:
  0 happens 2 times.
Training correct is: 0.75
Test correct is: 0.25
 y_1:
  z_1:
   x_1:
    1_is correct_3_times.
    0_is correct_1_times.
  z_0:
   1 happens 1 times.
 y_0:
  x_0:
   z_0:
    0 happens 2 times.
   z_1:
    1_is correct_1_times.
    0_is correct_1_times.
  x_1:
   z_0:
    0_is correct_1_times.
    1_is correct_1_times.
   z_1:
    0 happens 1 times.
Training correct is: 0.75
Test correct is: 0
 x_0:
  z_0:
   0 happens 2 times.
  z_1:
   y_0:
    0_is correct_1_times.
    1_is correct_1_times.
 x_1:
  z_1:
   y_0:
    1_is correct_1_times.
    0_is correct_1_times.
   y_1:
    1_is correct_3_times.
    0_is correct_1_times.
  z_0:
   1 happens 2 times.
Training correct is: 0.75
Test correct is: 0.25
