Our README says that GroupedMetadata should be handled by iterating over the object and treating the results as if they had been "unpacked" in the Annotated type. However, the docstring is specific to BaseMetadata, as is the type annotation:

The README is correct here, since we want to match typing.Unpack, so we should update the docstring to describe it as 'a grouping of multiple objects, like typing.Unpack', and annotate the iterable as containing object.

(originally identified in this downstream issue: HypothesisWorks/hypothesis#3986 (comment))