code: def _rfc3339_to_datetime(dt_str):
      
      return datetime.datetime.strptime(dt_str, _RFC3339_MICROS).replace(tzinfo=UTC)
docs: Convert a microsecond-precision timestamp to a native datetime.
  
      :type dt_str: str
      :param dt_str: The string to convert.
  
      :rtype: :class:`datetime.datetime`
      :returns: The datetime object created from the string.