msup1.test

<<< native
[ ESuper (EIdentifier "x") (ENumber "2") ]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <msup>
    <mi>x</mi>
    <mn>2</mn>
  </msup>
</math>