document save with skip_empty param in to_dict
document save with skip_empty param in to_dict

Document `save` method allows the parameter `skip_empty` to be set to `False` and passed to the method `to_dict`. Therefore the empty values (``None``, ``[]``, ``{}``) will be left on the document.
elastic/elasticsearch-dsl-py,3lnc/elasticsearch-dsl-py