code: def _get_session(session):
      """Common utility to get the session for the tensorflow-based explainer.
  
      Parameters
      ----------
      explainer : Explainer
  
          One of the tensorflow-based explainers.
  
      session : tf.compat.v1.Session
  
          An optional existing session.
      """
      _import_tf()
      # if we are not given a session find a default session
      if session is None:
          try:
              session = tf.compat.v1.keras.backend.get_session()
          except Exception:
              session = tf.keras.backend.get_session()
      return tf.get_default_session() if session is None else session
  
imports: import warnings
label_desc: Use image node_id 2 for calling a global function with example usage: _get_session(session) and returns: unknown