message: (NFC) Replace `NULL` with `nullptr`
diff: @@ -56,7 +56,7 @@ class Status {
  static Status OK() { return Status(); }
  /// Returns true iff the status indicates success.
  - bool ok() const { return (state_ == NULL); }
  + bool ok() const { return (state_ == nullptr); }
  tensorflow::error::Code code() const {
  return ok() ? tensorflow::error::OK : state_->code;
  