input: Write a function to calculate the accuracy of a classification model.
  assert calculate_accuracy(y_test, y_pred) == accuracy
  assert calculate_accuracy([0, 1, 1, 0], [0, 1, 0, 0]) == 0.75
  assert calculate_accuracy([1, 2, 3, 4], [1, 2, 3, 4]) == 1.0
output: def calculate_accuracy(y_test, y_pred):
      correct_predictions = sum(1 for yt, yp in zip(y_test, y_pred) if yt == yp)
      total_predictions = len(y_test)
      return correct_predictions / total_predictions