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<h1 id="4.3" class="anchor">
<a class="anchor__link link" href="#4.3" aria-hidden="true">#</a> <span class="number">4.3</span> <a class="link" href="https://mitp-content-server.mit.edu/books/content/sectbyfn/books_pres_0/6515/sicp.zip/full-text/book/book-Z-H-28.html">Variati