FacetWP replace double arrows (<<) with pointers (←)

<?php

// Add this to functions.php

add_filter( 'facetwp_pager_html', function( $output, $params ) {
    $output = str_replace( '<<', '←', $output );
    $output = str_replace( '>>', '→', $output );
    return $output;
}, 10, 2 );