code: def find(self, start, end, limit=50, *args, **kwargs):
          
          # check if spec has been specified, build on top of it
          fc = kwargs.get('spec', dict())
  
          # filter _id on start and end dates
          fc['_id'] = {'$gte': ObjectId.from_datetime(start),
                       '$lte': ObjectId.from_datetime(end)}
  
          if not self.collection:
              collection_name = kwargs.get('collection_name',
                               MONGODB_DEFAULT_COLLECTION)
              self.set_collection(collection_name)
  
          return self.collection.find(fc, limit=limit)
docs: find by creation date, using start and end dates as range