How to use the offlineimap.threadutil.InstanceLimitedThread function in offlineimap

for num, uid in enumerate(copylist):
            # bail out on CTRL-C or SIGTERM
            if offlineimap.accounts.Account.abort_NOW_signal.is_set():
                break
            if uid > 0 and dstfolder.uidexists(uid):
                # dst has message with that UID already, only update status
                flags = self.getmessageflags(uid)
                rtime = self.getmessagetime(uid)
                statusfolder.savemessage(uid, None, flags, rtime)
                continue

            self.ui.copyingmessage(uid, num+1, num_to_copy, self, dstfolder)
            # exceptions are caught in copymessageto()
            if self.suggeststhreads() and not globals.options.singlethreading:
                self.waitforthread()
                thread = threadutil.InstanceLimitedThread(\
                    self.getcopyinstancelimit(),
                    target = self.copymessageto,
                    name = "Copy message from %s:%s" % (self.repository, self),
                    args = (uid, dstfolder, statusfolder))
                thread.start()
                threads.append(thread)
            else:
                self.copymessageto(uid, dstfolder, statusfolder,
                                   register = 0)
        for thread in threads:
            thread.join()

        # Execute new mail hook if we have new mail
        if self.have_newmail:
            if self.newmail_hook != None:
                self.newmail_hook();

def syncitall(list_accounts, config):
    """The target when in multithreading mode for running accounts threads."""

    threads = threadutil.accountThreads() # The collection of accounts threads.
    for accountname in list_accounts:
        # Start a new thread per account and store it in the collection.
        account = accounts.SyncableAccount(config, accountname)
        thread = threadutil.InstanceLimitedThread(
            ACCOUNT_LIMITED_THREAD_NAME,
            target = account.syncrunner,
            name = "Account sync %s"% accountname
            )
        thread.setDaemon(True)
        # The add() method expects a started thread.
        thread.start()
        threads.add(thread)
    # Wait for the threads to finish.
    threads.wait() # Blocks until all accounts are processed.

def sync(self):
        # We don't need an account lock because syncitall() goes through
        # each account once, then waits for all to finish.
        try:
            remoterepos = self.remoterepos
            localrepos = self.localrepos
            statusrepos = self.statusrepos
            self.ui.syncfolders(remoterepos, localrepos)
            remoterepos.syncfoldersto(localrepos)

            folderthreads = []
            for remotefolder in remoterepos.getfolders():
                thread = InstanceLimitedThread(\
                    instancename = 'FOLDER_' + self.remoterepos.getname(),
                    target = syncfolder,
                    name = "Folder sync %s[%s]" % \
                    (self.name, remotefolder.getvisiblename()),
                    args = (self.name, remoterepos, remotefolder, localrepos,
                            statusrepos))
                thread.setDaemon(1)
                thread.start()
                folderthreads.append(thread)
            threadutil.threadsreset(folderthreads)
            mbnames.write()
            localrepos.holdordropconnections()
            remoterepos.holdordropconnections()
        finally:
            pass

def __init__(self, instancename, *args, **kwargs):
        self.instancename = instancename
        super(InstanceLimitedThread, self).__init__(*args, **kwargs)

def syncaccount(threads, config, accountname):
    account = SyncableAccount(config, accountname)
    thread = InstanceLimitedThread(instancename = 'ACCOUNTLIMIT',
                                   target = account.syncrunner,
                                   name = "Account sync %s" % accountname)
    thread.setDaemon(1)
    thread.start()
    threads.add(thread)

def syncaccount(config, accountname):
    """Return a new running thread for this account."""

    account = SyncableAccount(config, accountname)
    thread = InstanceLimitedThread(instancename = 'ACCOUNTLIMIT',
                                   target = account.syncrunner,
                                   name = "Account sync %s" % accountname)
    thread.setDaemon(True)
    thread.start()
    return thread

def syncaccount(threads, config, accountname):
    account = SyncableAccount(config, accountname)
    thread = InstanceLimitedThread(instancename = 'ACCOUNTLIMIT',
                                   target = account.syncrunner,
                                   name = "Account sync %s" % accountname)
    thread.setDaemon(1)
    thread.start()
    threads.add(thread)

else:
            quick = False

        try:
            remoterepos = self.remoterepos
            localrepos = self.localrepos
            statusrepos = self.statusrepos
            self.ui.syncfolders(remoterepos, localrepos)
            remoterepos.syncfoldersto(localrepos, [statusrepos])

            siglistener.addfolders(remoterepos.getfolders(), bool(self.refreshperiod), quick)

            while True:
                folderthreads = []
                for remotefolder, quick in siglistener.queuedfolders():
                    thread = InstanceLimitedThread(\
                        instancename = 'FOLDER_' + self.remoterepos.getname(),
                        target = syncfolder,
                        name = "Folder sync %s[%s]" % \
                        (self.name, remotefolder.getvisiblename()),
                        args = (self.name, remoterepos, remotefolder, localrepos,
                                statusrepos, quick))
                    thread.setDaemon(1)
                    thread.start()
                    folderthreads.append(thread)
                threadutil.threadsreset(folderthreads)
                if siglistener.clearfolders():
                    break
            mbnames.write()
            localrepos.forgetfolders()
            remoterepos.forgetfolders()
            localrepos.holdordropconnections()