Pakistan state/city extension for checkout page and shipping zones. Replaces states for cities

wc_pk_country_states.php

add_filter( 'woocommerce_countries',  'rs_edit_pk_country' );
function rs_edit_pk_country ( $countries ) {
  $new_countries = array(
	                    'PK'  => __( 'Pakistan', 'woocommerce' ),
	                    );

	return array_merge( $countries, $new_countries );
}

add_filter( 'woocommerce_continents', 'rs_add_new_pk_country_to_continents' );
function rs_add_new_pk_country_to_continents ( $continents ) {
	$continents['AS']['countries'][] = 'PK';
	return $continents;
}


add_filter( 'woocommerce_states', 'custom_wc_states_pk' );

function custom_wc_states_pk ( $states ) {

  $states['PK'] = array(

  		'Azad Kashmir' => 'Azad Kashmir',

	    'Quetta' => 'Quetta',
	    'Khuzdar' => 'Khuzdar',

	    'FATA' => 'FATA',

	    'Gilgit Baltistan' => 'Gilgit Baltistan',

	    'Islamabad' => 'Islamabad',

	    'Peshawar' => 'Peshawar',
        'Mardan' => 'Mardan',
        'Mingora' => 'Mingora',
        'Kohat' => 'Kohat',
        'Abbottabad' => 'Abbottabad',
        'Dera Ismail Khan' => 'Dera Ismail Khan',
        'Nowshera' => 'Nowshera',
        'Charsada' => 'Charsada',
        'Swabi ' => 'Swabi ',

    	'Lahore' => 'Lahore',
        'Faisalabad' => 'Faisalabad',
        'Rawalpindi' => 'Rawalpindi',
        'Multan' => 'Multan',
        'Gujranwala' => 'Gujranwala',
        'Sargodha' => 'Sargodha',
        'Sialkot' => 'Sialkot',
        'Sheikhupura' => 'Sheikhupura',
        'Gujrat' => 'Gujrat',
        'Kasur' => 'Kasur',
        'Rahim Yar Khan' => 'Rahim Yar Khan',
        'Sahiwal' => 'Sahiwal',
        'Okara' => 'Okara',
        'Wah Cantonment ' => 'Wah Cantonment ',
        'Dera Chazi Khan' => 'Dera Chazi Khan',
        'Chiniot' => 'Chiniot',
        'Kamoke' => 'Kamoke',
        'Burewala' => 'Burewala',
        'Jhelum' => 'Jhelum',
        'Sadiqabad' => 'Sadiqabad',
        'Khanewal' => 'Khanewal',
        'Hafizabad' => 'Hafizabad',
        'Khanpur' => 'Khanpur',
        'Gojra' => 'Gojra',
        'Bahawalnagar' => 'Bahawalnagar',
        'Muridke' => 'Muridke',
        'Pakpattan' => 'Pakpattan',
        'Jaranwala' => 'Jaranwala',
        'Chishtian' => 'Chishtian',
        'Daska' => 'Daska',
        'Mandi Bahauddin' => 'Mandi Bahauddin',
        'Ahmadpur East ' => 'Ahmadpur East ',
        'Kamalia' => 'Kamalia',
        'Vehari' => 'Vehari',
        'Wazirabad' => 'Wazirabad',
        'Khushab' => 'Khushab',
        'Chakwal' => 'Chakwal',
        'Mianwali' => 'Mianwali',
        'Kot Adu' => 'Kot Adu',
        'Farooka' => 'Farooka',
        'Chichawatni' => 'Chichawatni',

        'Karachi' => 'Karachi',
        'Hyderabad' => 'Hyderabad',
        'Sukkur' => 'Sukkur',
        'Kandhkot' => 'Kandhkot',
        'Larkana' => 'Larkana',
        'Mirpur Khas' => 'Mirpur Khas',
        'Nawabshah' => 'Nawabshah',
        'Jacobabad' => 'Jacobabad',
        'Shikapur' => 'Shikapur',
        'Tando Adam' => 'Tando Adam',
        'Khairpur' => 'Khairpur',
        'Dadu' => 'Dadu',
        'Tando Allahyar' => 'Tando Allahyar',

 );

  return $states;
}

Can someone please tell me how to use this code?