datastore/datastore.go
func DeleteMulti(c context.Context, key []*Key) error {
	if len(key) == 0 {
		return nil
	}
	if err := multiValid(key); err != nil {
		return err
	}
	req := &pb.DeleteRequest{
		Key: multiKeyToProto(internal.FullyQualifiedAppID(c), key),
	}
	res := &pb.DeleteResponse{}
	return internal.Call(c, "datastore_v3", "Delete", req, res)
}
func DeleteMulti(c context.Context, key []*Key) error {
	if len(key) == 0 {
		return nil
	}
	if err := multiValid(key); err != nil {
		return err
	}
	req := &pb.DeleteRequest{
		Key: multiKeyToProto(internal.FullyQualifiedAppID(c), key),
	}
	res := &pb.DeleteResponse{}
	return internal.Call(c, "datastore_v3", "Delete", req, res)
}
// DeleteMulti is a batch version of Delete.