{"ast_node_type":"function","tokens":[{"end":83,"kind":"keyword","start":0,"text":"pub"}]}
    pub fn first_unset_in(&self, range: impl RangeBounds<I> + Clone) -> Option<I> {
    /// Equivalent to `range.iter().find(|i| !self.contains(i))`.
        let start = inclusive_start(range.clone());