Function lazy_expand 

fn lazy_expand<'db>(
    db: &'db dyn SourceDatabase,
    def: &MacroDefId,
    macro_call: &MacroCall,
    ast_id: AstId<MacroCall>,
    krate: Crate,
    call_site: SyntaxContext,
    eager_callback: EagerCallBackFn<'_>,
) -> ExpandResult<(InFile<Parse<SyntaxNode>>, &'db ExpansionSpanMap)>