{"ast_node_type":"function","tokens":[{"end":65,"kind":"keyword","start":0,"text":"pub(crate)"}]}
    pub(crate) fn equate(&mut self, a: ty::TyVid, b: ty::TyVid) {
    /// Precondition: neither `a` nor `b` are known.
        debug_assert!(self.probe(a).is_unknown());