fn show_substructure(
cx: &ExtCtxt<'_>,
span: Span,
substr: Substructure<'_>,
type_ident: Ident,
) -> BlockOrExprfn show_substructure(
cx: &ExtCtxt<'_>,
span: Span,
substr: Substructure<'_>,
type_ident: Ident,
) -> BlockOrExpr