human
I wrote the below code

    def acquire_mutex():
        account_name = account.getname()
        localfolder_name = localfolder.getfullname()
        with SYNC_MUTEXES_LOCK:
            if (SYNC_MUTEXES.get(account_name) is None):
                SYNC_MUTEXES[account_name] = {}
            if (SYNC_MUTEXES[account_name].get(localfolder_name) is None):
                SYNC_MUTEXES[account_name][localfolder_name] = Lock()
        SYNC_MUTEXES[account_name][localfolder_name].acquire()
    def release_mutex():
        SYNC_MUTEXES[account.getname()][localfolder.getfullname()].release()
    def check_uid_validity():
        if ((localfolder.getmessagecount() > 0) or (statusfolder.getmessagecount() > 0)):
            if (not localfolder.check_uidvalidity()):
                ui.validityproblem(localfolder)
                localfolder.repository.restore_atime()
                return
            if (not remotefolder.check_uidvalidity()):
                ui.validityproblem(remotefolder)
                localrepos.restore_atime()
                return
        else:
            localfolder.save_uidvalidity()
            remotefolder.save_uidvalidity()
    def cachemessagelists_upto_date(date):
        'Returns    messages    with    uid    >    min(uids    of    messages    newer    than    date).'
        remotefolder.cachemessagelist(min_date=time.gmtime((time.mktime(date) + ((24 * 60) * 60))))
        uids = remotefolder.getmessageuidlist()
        localfolder.dropmessagelistcache()
        if (len(uids) > 0):
            localfolder.cachemessagelist(min_uid=min(uids))
        else:
            localfolder.cachemessagelist(min_date=date)
            uids = localfolder.getmessageuidlist()
            if (len(uids) > 0):
                remotefolder.cachemessagelist(min_uid=min(uids))
    def cachemessagelists_startdate(new, partial, date):
        "Retrieve    messagelists    when    startdate    has    been    set    for\n                                the    folder    'partial'.\n\n                                Idea:    suppose    you...

What's a good function header?
assistant
#Here's a good function header.

def syncfolder(account, remotefolder, quick):