public function dependancy_errors($dependentlesson, $errors) {
        $output  = $this->output->box_start('generalbox boxaligncenter');
        $output .= get_string('completethefollowingconditions', 'lesson', $dependentlesson->name);
        $output .= $this->output->box(implode('<br />'.get_string('and', 'lesson').'<br />', $errors),'center');
        $output .= $this->output->box_end();
        return $output;
    }