code: def make_full_tz_list():
      dateutil_zones = set(get_zonefile_instance().zones)
      pytz_zones = set(pytz.all_timezones)
      return dateutil_zones.union(pytz_zones)
  
imports: import pytz
  from dateutil.zoneinfo import get_zonefile_instance
label_desc: Use image node_id 1 for calling a global function with example usage: make_full_tz_list() and returns: dateutil_zones