code: def find(self, selector, collation=None):
          
          validate_is_mapping("selector", selector)
          return BulkWriteOperation(selector, self.__bulk, collation)
docs: Specify selection criteria for bulk operations.
  
          :Parameters:
            - `selector` (dict): the selection criteria for update
              and remove operations.
            - `collation` (optional): An instance of
              :class:`~pymongo.collation.Collation`. This option is only
              supported on MongoDB 3.4 and above.
  
          :Returns:
            - A :class:`BulkWriteOperation` instance, used to add
              update and remove operations to this bulk operation.
  
          .. versionchanged:: 3.4
             Added the `collation` option.