deletePages method
Implementation
Future<bool> deletePages(List<int> indices) async {
final Set<int> doomed = indices.toSet();
final List<UPdfRef> refs = await flattenPageTree();
final List<UPdfRef> kept = <UPdfRef>[];
for (int i = 0; i < refs.length; i++) {
if (!doomed.contains(i)) kept.add(refs[i]);
}
if (kept.isEmpty || kept.length == refs.length) return false;
return setPageOrder(kept);
}