Custom Result Count with FacetWP

<?php
// customize result count output
add_filter( 'facetwp_result_count', function( $output, $params ) {
    $output = 'Dispalying <span class="results-visible">' . $params['lower'] . '-' . $params['upper'] . '</span> of <span class="results-total">' . $params['total'] . '</span> results';
    return $output;
}, 10, 2 );