add_shortcode('countriesDropdown', 'countriesDropdown_shortcode');
  function countriesDropdown_shortcode( $atts = [], $content = null) {
    ?>
    <div>
      <form action="#" method="post">
          <select name="countrySel" id="_countryDropdown" onchange="this.form.submit()">
            <option value="" selected disabled hidden>Select Country</option>
             <?php
             Global $countries2;
             $listOfCountries = array_keys($countries2);
             sort($listOfCountries);
             foreach( $listOfCountries as $country ) { ?>
               <option value="<?php echo $country; ?>"><?php echo $country; ?></option>
             <?php
             }
             ?>
           </select>
        </form>
     </div>
       <?php

     return '';
  }