[o] volute 'prev' => 'new' { ... }
[o] volute Module { ... }
[o] obj.volute_do_set(:a => 0, :b => 1)
[o] volute { over }

[ ] volute /^att/ { ... }
[ ] volute /regex/ => /regex/ { ... }

[ ] volute do
      volute Invoice do
        volute :paid do
    
          if is(true)
            object.comment = 'got paid'
          elsif was(nil)
            object.comment = 'still not paid'
          end
        end
      end
    end

[ ] multi-entity state machine example