Description:
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I am using DOMDocument to pretty-print XML files:

$domDocument = new DomDocument();
$domDocument->preserveWhiteSpace = false;
$domDocument->formatOutput = true;
$domDocument->loadXML($uglyXml);
$prettyXml = $domDocument->saveXML();

The identiation width is hardcoded with 2 spaces. I would like to be able to specify a custom identiation width, something like

$domDocument->indentWidth = 4;

Test script:
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$domDocument = new DomDocument();
$domDocument->preserveWhiteSpace = false;
$domDocument->formatOutput = true;
$domDocument->indentWidth = 4;
$domDocument->loadXML($uglyXml);
$prettyXml = $domDocument->saveXML();