code: def rfc3339_datetime(dt: datetime.datetime) -> str:
      """
      Return a datetime in RFC3339 format.
  
      datetime.utcnow().isoformat() is so close -- it's just missing the UTC timezone suffix!
      Go requires this to be able to parse it using the default time.Time parser.
  
      datetime.now(timezone.utc) is almost it, but uses +00:00 instead of the Z shorthand.
  
      https://bugs.python.org/issue35829 for the inverse problem.
      """
      assert (
          dt.tzinfo is None
      ), "rfc3339_datetime() only works with naive datetime objects"
      return dt.isoformat() + "Z"
  
label_desc: Use image node_id 1 for calling a global function with example usage: rfc3339_datetime(dt) and returns: unknown