class_docstr: Computes the MSE loss between true labels and predicted labels.
code: def grad(self, y_true, y_pred):
      batch_size = y_true.shape.as_list()[0]
      batch_size_inv = 1 / batch_size
      return 2 * (y_pred - y_true) * batch_size_inv
  
imports: import tf_encrypted
label_desc: Use image node_id 2 for calling the MeanSquaredError obj's underlying member method code with example usage: obj.grad(y_true, y_pred) and returns: unknown