{"ast_node_type":"variable","tokens":[{"end":82,"kind":"keyword","start":0,"text":"let"}]}
        let (index, _) = self.source_loc_set.insert_full((file_id, line, column));
    pub(crate) fn add_dbg_loc(&mut self, file_id: FileId, line: u64, column: u64) -> SourceLoc {
        SourceLoc::new(u32::try_from(index).unwrap())