code: def variables_accessed(variables):
      """Notifies all tapes in the stack that variables have been accessed.
  
      Only trainable variables are marked as accessed.
  
      Args:
        variables: iterable of variables to mark as accessed.
      """
      accessed = []
      for variable in variables:
          if variable.trainable:
              accessed.extend(_variables_override(variable))
  
      for var in accessed:
          pywrap_tfe.TFE_Py_TapeVariableAccessed(var)
          pywrap_tfe.TFE_Py_VariableWatcherVariableAccessed(var)
  
file_path: tensorflow-upstream/tensorflow/python/eager/tape.py
imports: from tensorflow.python import pywrap_tfe
label_desc: Use image node_id 8 for calling a global function with example usage: variables_accessed(variables) without return types