code: def find_by_id(self, _id, projection=None):
          
          if isinstance(_id, list) or isinstance(_id, tuple):
              return list(self.__collect.find(
                  {'_id': {'$in': [self._to_primary_key(i) for i in _id]}}, projection))
  
          document_id = self._to_primary_key(_id)
  
          if document_id is None:
              return None
  
          return self.__collect.find_one({'_id': document_id}, projection)
docs: find record by _id