Unit timings print on certificate

functions.php

add_shortcode('certificate_course_unit_timings',function($atts,$content=null){
$return = '';
$course_id = ;
$user_id = ;
$course_curriculum = bp_course_get_curriculum( $course_id );

$unit_timing = array();

$init = WPLMS_Unit_Timings_Init::Instance_WPLMS_Unit_Timings_Init();

foreach ($course_curriculum as $unit_id) {
  if( is_numeric($unit_id) ){
    $unit_timing[] = array('unit'=>get_the_title($unit_id),'time'=>$init->get_course_unit_time_spent( $user_id,$course_id,$unit_id ));
  }
}

if(!empty($unit_timing)){
  foreach ($unit_timing as $unit) {
    $return .='<div><label>'.$unit['unit'].'</label><span>'.tofriendlytime($unit['time']).'</span></div>';
  }
}
return $return;
});