How to add "swing" style to the music21 output for MuseScore

Question

I'm writing jazz pieces using music21, and then exporting them to MuseScore with stream.show(). Before playing the song, I use the Text palette in MuseScore to add "Swing" over the first note, and then the playback has a swing feel to it. I was wondering if I could add this directly using music21.

Saving the modified musicXML file, I noticed that the first measure contains a block with the information needed for swing style, but I haven't found a mechanism that allows me to add this using music21. Here's what the musicXML file looks like with the needed elements for swing style:

<Measure>
    <voice>
      <Clef>
        <concertClefType>G</concertClefType>
        <transposingClefType>G</transposingClefType>
        </Clef>
      <TimeSig>
        <sigN>4</sigN>
        <sigD>4</sigD>
        </TimeSig>
      <Tempo>
        <tempo>2.66667</tempo>
        <followText>1</followText>
        <text><sym>metNoteHalfUp</sym> = 80</text>
        </Tempo>
      <SystemText>
        <swing unit="eighth" ratio="60"/>
        <style>tempo</style>
        <text>Swing</text>
        </SystemText>