{"ast_node_type":"other","tokens":[{"end":51,"kind":"keyword","start":0,"text":"#[instrument(skip(self),"}]}
    #[instrument(skip(self), level = "trace", ret)]
    /// Finds some region R such that `fr1: R` and `R` is live at `location`.
    pub(crate) fn find_sub_region_live_at(&self, fr1: RegionVid, location: Location) -> RegionVid {