<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def CER(prediction, true_labels):
 """ Calculates the classification error rate for an N-class classification problem Parameters: prediction (numpy.ndarray):
 A 1D :py:class:`numpy.ndarray` containing your prediction true_labels (numpy.ndarray):
 A 1D :py:class:`numpy.ndarray` containing the ground truth labels for the input array, organized in the same order. """


  errors = (prediction != true_labels).sum()
  return float(errors)/len(prediction)