S12 describes a feature to call sets of methods at the same time:
I would like the spec to clarify what happens to the return values of
all these methods.
I'm fine with a simple answer, such as that they are not available, or
only the first or last set of return values is returned.
As a "use case", we may use of basically this feature in
CGI::Application in Perl5, as part the plugin system. Each plugin
location is like a method name, and as we get to each point in the code,
we look up through the inheritance tree, executing methods at each location.
In this case, I think we ignore the return values.