def accuracy(conf_matrix):
  """
  Given a confusion matrix, returns the accuracy.
  Accuracy Definition: http://research.ics.aalto.fi/events/eyechallenge2005/evaluation.shtml
  """
  total, correct = 0.0, 0.0
  for true_response, guess_dict in conf_matrix.items():
    for guess, count in guess_dict.items():
      if true_response == guess:
        correct += count
      total += count
  return correct/total
Given a confusion matrix, returns the accuracy.
  Accuracy Definition: http://research.ics.aalto.fi/events/eyechallenge2005/evaluation.shtml