'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.'

def find(self, selector, collation=None):

    validate_is_mapping('selector', selector)
    return BulkWriteOperation(selector, self.__bulk, collation)
