{"ast_node_type":"function","tokens":[{"end":82,"kind":"keyword","start":0,"text":"fn"}]}
    fn extend_deduped(&mut self, clauses: impl IntoIterator<Item = WhereClause>) {
impl ClauseElaborator<'_> {
        self.stack.extend(clauses.into_iter().filter(|c| self.seen.insert(c.clone())))