new_contents: import functools
  from django.core.cache import cache
  
  def single_instance_task(timeout):
      def task_exc(func):
          @functools.wraps(func)
          def wrapper(*args, **kwargs):
              lock_id = "celery-single-instance-" + func.__name__
              acquire_lock = lambda: cache.add(lock_id, "true", timeout)
              release_lock = lambda: cache.delete(lock_id)
              if acquire_lock():
                  try:
                      func(*args, **kwargs)
                  finally:
                      release_lock()
          return wrapper
      return task_exc
subject: Add in single instance task file