{"ast_node_type":"function","tokens":[{"end":50,"kind":"keyword","start":0,"text":"pub"}]}
    pub fn expect_const(self) -> ty::Const<'tcx> {
    /// Unpack the `GenericArg` as a const when it is known certainly to be a const.
        self.as_const().unwrap_or_else(|| bug!("expected a const, but found another kind"))