fn assert_expand(
db: &dyn SourceDatabase,
id: MacroCallId,
tt: &TopSubtree,
span: Span,
) -> ExpandResult<TopSubtree>fn assert_expand(
db: &dyn SourceDatabase,
id: MacroCallId,
tt: &TopSubtree,
span: Span,
) -> ExpandResult<TopSubtree>