human
Solve the following python programming problem given the following code:
def _process_repo(repo, unused_repo_name, args, arcyd_conduit, url_watcher, mail_sender) : 
    fetch_if_needed (url_watcher, abdi_repoargs.get_repo_snoop_url (args), repo, args.repo_desc) 
    admin_emails = set (_flatten_list (args.admin_emails)) 
    mailer = abdmail_mailer.Mailer (mail_sender, admin_emails, args.repo_desc, args.instance_uri) 
    branch_url_callable = None 
    if mailer.branch_url_format : 
        def make_branch_url(branch_name) : 
            return args.branch_url_format.format (branch = branch_name, repo_url = args.repo_url) 
branch_url_callable = make_branch_url 
branch_naming = abdt_compositenaming.Naming (abdt_classicnaming.Naming (), abdt_rbranchnaming.Naming ()) 
    branches = abdt_git.get_managed_branches (repo, args.repo_desc, branch_naming, branch_url_callable) 
    abdi_processrepo.process_branches (branches, arcyd_conduit, mailer) 

    
    

    Fix the buggy line: if mailer.branch_url_format :
assistant
#Here is Python code to fix the buggy line: if mailer.

if args.branch_url_format :