'Create a DeleteMany instance.
For use with :meth:`~pymongo.collection.Collection.bulk_write`.
:Parameters:
- `filter`: A query that matches the documents to delete.
- `collation` (optional): An instance of
:class:`~pymongo.collation.Collation`. This option is only
supported on MongoDB 3.4 and above.
.. versionchanged:: 3.5
Added the `collation` option.'

def __init__(self, filter, collation=None):

    if (filter is not None):
        validate_is_mapping('filter', filter)
    self._filter = filter
    self._collation = collation
