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<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script>
function ocultarmostrar(){
ver = document.getElementById("div").style.display;
if (ver=='none'){
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document.getElementById("div").style.display="none ";
}
}
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<title>Documento sin título</title>
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<div id="div" >Colocar aquí el contenido para id "div"</div>
<p>
<label>
<input type="submit" name="button" id="button" value="Enviar" onclick="ocultarmostrar()"/>
</label>
</p>
</body>
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