{"ast_node_type":"variable","tokens":[{"end":57,"kind":"keyword","start":0,"text":"let"}]}
    let (span, _) = source_span_for_markdown_range_inner(
    sm.new_source_file(PathBuf::from("foo.rs").into(), r#"#[doc = "`"] fn foo() {}"#.to_string());
        &sm,