{"ast_node_type":"function","tokens":[{"end":80,"kind":"keyword","start":0,"text":"//"}]}
            // The closure fn is a `fn(&self, ...)` or `fn(&mut self, ...)`, but
        (ty::ClosureKind::Fn | ty::ClosureKind::FnMut, ty::ClosureKind::FnOnce) => {
            // we want a `fn(self, ...)`. We can produce this by doing something like: