code: def __enter__(self):
      self._existing_vars = contextvars.merge_contextvars(
          logger=None, method_name=None, event_dict={}
      )
      contextvars.bind_contextvars(**self._context)
      return self
  
imports: from structlog import contextvars
label_desc: Use image node_id 2 for calling the ContextualizedLogging obj's underlying member method code with example usage: obj.__enter__() and returns: self