input: Write a python function to classify features based on a decision boundary.
  assert classify([[6, 3], [4, 1], [7, 5]], ['ClassA', 'ClassB']) == ['ClassA', 'ClassB', 'ClassA']
  assert classify([[5, 2], [3, 8], [6, 0]], ['High', 'Low']) == ['Low', 'Low', 'High']
  assert classify([[10], [2], [5], [7]], ['Yes', 'No']) == ['Yes', 'No', 'No', 'Yes']
output: def classify(features, classes):
      decision_boundary = sum(sum(feature) for feature in features) / (len(features) * len(features[0]))
      return [classes[0] if sum(feature) >= decision_boundary else classes[1] for feature in features]