parseXmlTag function
Parse content from an XML tag.
Implementation
String? parseXmlTag(String text, String tag) {
final openTag = '<$tag>';
final closeTag = '</$tag>';
final start = text.indexOf(openTag);
if (start == -1) return null;
final contentStart = start + openTag.length;
final end = text.indexOf(closeTag, contentStart);
if (end == -1) return null;
return text.substring(contentStart, end).trim();
}