Nested Keynote slides with Applescript

Question

Is there a way to achieve this:

when creating a presentation programatically via Applescript?

As an aside the code I have now looks like this:

tell application "Keynote"
    set themeprops to {theme:"Gradient", slideSize:{800, 600}}
    set s to make new slideshow at end of slideshows with data themeprops
    repeat with content in {"a", "b", "c", "d"}
        tell s
            set titleMaster to item 7 of master slides -- using magic number :(
            set newslide to make new slide
            tell current slide
                set title to content
                set master to titleMaster
            end tell
        end tell
    end repeat
end tell

For ideas about workarounds: My app will generate this code from a Markdown document, thus enabling writing your presentation in Markdown. I hoped that different levels of headings could mea different levels of nesting in the final output.