texmath-0.12.5: test/writer/mml/msupBnest1.test

<<< native
[ EIdentifier "x"
, ESymbol Bin "+"
, ESuper (EIdentifier "y") (EIdentifier "n")
]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
    <mi>x</mi>
    <mo>+</mo>
    <msup>
      <mi>y</mi>
      <mi>n</mi>
    </msup>
  </mrow>
</math>