message: Fix typo in GradientTape.persistent_ comment.
diff: @@ -161,7 +161,7 @@ class GradientTape {
  // the tape refer to it); to aid in tape garbage collection.
  std::unordered_map<int64, int64> tensor_usage_;
  - // If true, all activations are deleted in the first call to ComputeGradient.
  + // If false, all activations are deleted in the first call to ComputeGradient.
  // Else, only when this is destructed.
  bool persistent_;
  };
  