class_docstr: A Python context for wrapping a cancellable ConcreteFunction.
code: def __enter__(self):
      global _active_context
      _active_context = self._cancellation_manager
  
file_path: tensorflow-upstream/tensorflow/python/eager/cancellation.py
imports: from tensorflow.python import pywrap_tfe
label_desc: Use image node_id 2 for calling the CancellationManagerContext obj's underlying member method code with example usage: obj.__enter__() without return types