class_docstr: An internal class to track the lifetime of a Tensor.
class_docstr_tok: ["An","internal","class","to","track","the","lifetime","of","a","Tensor","."]
docstr: Adds a reference to this tensor with the specified timestamp.
  
  Args:
    timestamp:  Timestamp of object reference as an integer.
docstr_tok: ["Adds","a","reference","to","this","tensor","with","the","specified","timestamp",".","Args",":","timestamp",":","Timestamp","of","object","reference","as","an","integer","."]
code: def add_ref(self, timestamp: int) -> None:
      """Adds a reference to this tensor with the specified timestamp.
  
      Args:
        timestamp:  Timestamp of object reference as an integer.
      """
      self._ref_times.append(timestamp)
  
imports: import collections
  import copy
  import json
  import re
  from typing import Any, Dict, List, Optional, Tuple, Union
  from tensorflow.core.framework import step_stats_pb2
  from tensorflow.python.platform import build_info
  from tensorflow.python.platform import tf_logging
label_desc: Use image node_id 9 for calling the _TensorTracker obj's underlying member method code with example usage: obj.add_ref(timestamp) without return types