Define a function with a `setof` return type

Describe the solution you'd like

A simple way to define a function that returns setof something for set returning functions. Perhaps a toggle called Returns a set? that when activated will define the specified Return type as setof.

Describe alternatives you've considered

Just clicking the Custom return type? toggle, and typing in setof <my type>. This works, but I don't get to use the dropdown list that has my type.

Additional context

Here is a proposed screen snip of how this could look, with a Returns a set? toggle under the Custom return type? toggle.

Thanks!

Start by tracing the existing Custom return type? toggle and return-type dropdown in the function-definition UI. Confirm how the selected type is represented for set-returning functions, then verify that enabling Returns a set? produces a setof return type while preserving dropdown selection.