class_docstr: Packed representation of compressed tensors.
  
  This class can pack and unpack several tensor values into a single string. It
  can also optionally store a model identifier.
  
  The tensors currently must be rank 1 (vectors) and either have integer or
  string type.
code: def __init__(self, string=None):
      self._example = tf.train.Example()
      if string:
          self.string = string
  
file_path: compression/tensorflow_compression/python/util/packed_tensors.py
imports: import tensorflow
label_desc: Use image node_id 1 to create a new PackedTensors object  with example: obj = PackedTensors(string)