Fix astuple in dataclasses documentation (GH-9631)
diff --git a/Doc/library/dataclasses.rst b/Doc/library/dataclasses.rst
index acfd13a..072a500 100644
--- a/Doc/library/dataclasses.rst
+++ b/Doc/library/dataclasses.rst
@@ -308,7 +308,7 @@
Raises :exc:`TypeError` if ``instance`` is not a dataclass instance.
-.. function:: astuple(*, tuple_factory=tuple)
+.. function:: astuple(instance, *, tuple_factory=tuple)
Converts the dataclass ``instance`` to a tuple (by using the
factory function ``tuple_factory``). Each dataclass is converted