<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def peak_signal_to_noise_ratio(true, pred):
 """Image quality metric based on maximal signal power vs. power of the noise. Args: true: the ground truth image. pred: the predicted image. Returns: peak signal to noise ratio (PSNR) """

  return 10.0 * tf.log(1.0 / mean_squared_error(true, pred)) / tf.log(10.0)