class_docstr: A scope that tracks all trainable variable accesses within it.
  
  This explicitly ignores variables that are not marked as trainable.
  
  Sample usage:
  
  var = tf.Variable(0.0)
  with VariableWatcher() as variable_watcher:
    var.assign_add(1.0)
  
  assert variable_watcher.watched_variables == [var]
code: def __enter__(self):
      self._variable_watcher = pywrap_tfe.TFE_Py_VariableWatcherNew()
      return self
  
file_path: tensorflow/tensorflow/python/eager/record.py
imports: import contextlib
  from tensorflow.python import pywrap_tfe
label_desc: Use image node_id 2 for calling the VariableWatcher obj's underlying member method code with example usage: obj.__enter__() and returns: self