mport msgpack
mport twisted.internet.defer as defer
mport twisted.internet.threads as threads
lass Store(object):
 def load(self, key: str) -> defer.Deferred:
   pass
 def store(self, key: str, data: bytes) -> defer.Deferred:
   pass
 def delete(self, key: str) -> defer.Deferred:
   pass
ef readFile(name: str) -> defer.Deferred:
 print('readFile')
 def inThread():
   print('readFile > inThread')
   with open(name, 'r+b') as fd:
     return fd.read()
 return threads.deferToThread(inThread)
ef writeFile(name: str, data: bytes) -> defer.Deferred:
 print('writeFile')
 def inThread():
   print('writeFile > inThread')
   with open(name, 'w+b') as fd:
     return fd.write(data)
 return threads.deferToThread(inThread)
lass FileStore(Store):
 def __init__(self, name):
   self.__name = name
   self.__data = {}
   self.__last = self.__readData()
 @defer.inlineCallbacks
 def __readData(self):
   data = yield readFile(self.__name)
   data = msgpack.unpackb(data, encoding='utf-8')
   if isinstance(data, dict):
     self.__data = data
 @property
 def name(self):
   return self.__name
 def __queue(self, job) -> defer.Deferred:
   d = defer.Deferred()
   def trampolineSucceed(result):
     if isinstance(result, defer.Deferred):
       result.addCallbacks(trampolineSucceed, trampolineFail)
     else:
       d.callback(result)
   def trampolineFail(result):
     if isinstance(result, defer.Deferred):
       result.addCallbacks(trampolineSucceed, trampolineFail)
     else:
       d.errback(result)
   self.__last.addBoth(lambda _: job())
   self.__last.addCallbacks(trampolineSucceed, trampolineFail)
   return d
 def load(self, key: str) -> defer.Deferred:
   def job():
     return self.__data[key] if key in self.__data else None
   return self.__queue(job)
 def store(self, key: str, data) -> defer.Deferred:
   def job():
     self.__data[key] = data
     return writeFile(self.__name, msgpack.packb(self.__data, use_bin_type=True))
   return self.__queue(job)
 def delete(self, key: str) -> defer.Deferred:
   def job():
     if key in self.__data:
       del self.__data[key]
       return writeFile(self.__name, msgpack.packb(self.__data, use_bin_type=True))
   return self.__queue(job)