HTML heading hierarchy for XHTML [RE-POST]

I'd like to preserve the implicit hierarchy of HTML headings when
converting to XHTML. For example, I'd like to end up with this XHTML
output:

<h1>Heading 1 text
        <h2>Heading 2 under heading 1</h2>
given this HTML input:

<h1>Heading 1 text</h1>Would this translation be feasible as an option in Tidy?
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