#_COUNTRYFLAG

function em_country_flag( $replace, $EM_Event, $result ) {
    if ( $result == '#_COUNTRYFLAG' ) {
        $country_code = $EM_Event->location->country;
        if ( $country_code ) {
            $country_code = strtolower( $country_code );
            $replace      = '<img src="' . get_stylesheet_directory_uri() . '/assets/img/flags/' . $country_code . '.png" alt="" class="flag" />';
        } else {
            $replace = false;
        }
    }

    return $replace;
}
add_filter( 'em_event_output_placeholder', 'em_country_flag', 1, 3 );