Fungsi Date timezone_identifiers_list() PHP

<?php
print_r(timezone_identifiers_list(1));
?>
  // Output : Array ( [0] => Africa/Abidjan [1] => Africa/Accra [2] => Africa/Addis_Ababa [3] => Africa/Algiers [4] => Africa/Asmara [5] => Africa/Bamako [6] => Africa/Bangui [7] => Africa/Banjul [8] => Africa/Bissau [9] => Africa/Blantyre [10] => Africa/Brazzaville [11] => Africa/Bujumbura [12] => Africa/Cairo [13] => Africa/Casablanca [14] => Africa/Ceuta [15] => Africa/Conakry [16] => Africa/Dakar [17] => Africa/Dar_es_Salaam [18] => Africa/Djibouti [19] => Africa/Douala [20] => Africa/El_Aaiun [21] => Africa/Freetown [22] => Africa/Gaborone [23] => Africa/Harare [24] => Africa/Johannesburg [25] => Africa/Juba [26] => Africa/Kampala [27] => Africa/Khartoum [28] => Africa/Kigali [29] => Africa/Kinshasa [30] => Africa/Lagos [31] => Africa/Libreville [32] => Africa/Lome [33] => Africa/Luanda [34] => Africa/Lubumbashi [35] => Africa/Lusaka [36] => Africa/Malabo [37] => Africa/Maputo [38] => Africa/Maseru [39] => Africa/Mbabane [40] => Africa/Mogadishu [41] => Africa/Monrovia [42] => Africa/Nairobi [43] => Africa/Ndjamena [44] => Africa/Niamey [45] => Africa/Nouakchott [46] => Africa/Ouagadougou [47] => Africa/Porto-Novo [48] => Africa/Sao_Tome [49] => Africa/Tripoli [50] => Africa/Tunis [51] => Africa/Windhoek )