message: Make stubs happy
diff: @@ -116,6 +116,7 @@ class DuckDBPyRelation:
  def sum(self, sum_aggr: str, group_expr: str = ...) -> DuckDBPyRelation: ...
  def to_arrow_table(self, batch_size: int = ...) -> object: ...
  def to_df(self) -> object: ...
  + def explain(self) -> str: ...
  @overload
  def union(self, union_rel: DuckDBPyRelation) -> DuckDBPyRelation: ...
  @overload
  