def init(
        cls, index: Optional[str] = None, using: Optional[UsingType] = None
    ) -> None:
        """
        Create the index and populate the mappings in elasticsearch.
        """
        i = cls._index
        if index:
            i = i.clone(name=index)
        i.save(using=using)

        Create the index and populate the mappings in elasticsearch.
        
elasticsearch/dsl/_sync/document.py