in lib/printer.dart [152:167]
void add(object,
{SourceLocation? location, SourceSpan? span, bool isOriginal = false}) {
if (object is! String || location != null || span != null || isOriginal) {
_flush();
assert(location == null || span == null);
if (location != null) _items.add(location);
if (span != null) _items.add(span);
if (isOriginal) _items.add(_original);
}
if (object is String) {
_appendString(object);
} else {
_items.add(object);
}
}