$net->iterations(100000); # let's have lots more iterations!
  $net->iterations;         # returns 100000
  my @training_data = (
    [1,1], [0,1],
    [1,0], [0,1],
    [0,1], [0,1],
    [0,0], [1,0],
  );
  $net->train_set(\@training_data);