texmath-0.13.1.2: test/writer/mml/msub-01.test

<<< native
[ ESub (EIdentifier "L") (EIdentifier "x")
, ESymbol Rel "="
, ESub
    (EIdentifier "L")
    (EGrouped [ EIdentifier "x" , EPhantom (EIdentifier "fail") ])
]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
    <msub>
      <mi>L</mi>
      <mi>x</mi>
    </msub>
    <mo>=</mo>
    <msub>
      <mi>L</mi>
      <mrow>
        <mi>x</mi>
        <mphantom>
          <mi>fail</mi>
        </mphantom>
      </mrow>
    </msub>
  </mrow>
</math>