human
Solve the following python programming problem given the following code:
def add_cluster_templates(ctx, clusters, ng_dict) : 
    'Add cluster templates to the database.

    The value of any node_group_template_id fields in cluster
    templates which reference a node group template in ng_dict by name
    will be changed to the id of the node group template.

    If there is an error in creating or updating a template, any templates
    that have already been created will be delete and any updates will
    be reversed.

    :param clusters: a list of dictionaries. Each dictionary
                     has a "template" entry holding the cluster template
                     and a "path" entry holding the path of the file
                     from which the template was read.
    :param ng_dict: a dictionary of node group template ids keyed
                    by node group template names
    ' 
    error = False 
    created = [] 
    updated = [] 
    def do_reversals(created, updated) : 
        reverse_cluster_template_updates (ctx, updated) 
        reverse_cluster_template_creates (ctx, created) 
        return True 
try : 
        for cl in clusters : 
            template = cl ['template'] 
            u.substitute_ng_ids (template, ng_dict) 
            current = u.find_cluster_template_by_name (ctx, template ['name']) 
            if current : 
                updated_fields = u.value_diff (current.to_dict (), ctx) 
                try : 
                    template = conductor.API.cluster_template_update (ctx, current ['id'], template, ignore_prot_on_def = True) 
except Exception as e : 
                    LOG.warning (_LW ('Update of cluster template {info} failed, {reason}').format (info = u.name_and_id (current), reason = e)) 
                    raise Handled () 
if (template ['updated_at'] != current ['updated_at']) : 
                    updated.append ((template, updated_fields)) 
                    LOG.info (_LI ('Updated cluster template {info} from {path}').format (info = u.name_and_id (template), path = cl ['path'])) 
else : 
                    LOG.debug...

    
    

    Fix the buggy line: updated_fields = u.value_diff (current.to_dict (), ctx)
assistant
#Here is Python code to fix the buggy line: updated_fields = u.

updated_fields = u.value_diff (current.to_dict (), template)