code: def default_session() -> boto3.Session:
      """
      Returns the shared session to be used.
      """
      global _SESSION  # pylint: disable=global-statement
      if _SESSION is None:
          _SESSION = boto3.Session()  # type: ignore
      return _SESSION
  
label_desc: Use image node_id 1 for calling a global function with example usage: default_session() and returns: _SESSION