{"ast_node_type":"variable","tokens":[{"end":78,"kind":"keyword","start":0,"text":"///"}]}
    /// let y = (&mut Env { x: &mut x }, fn_ptr); // changed from &x to &mut x
    /// let x: &mut isize = &mut z;
    /// fn fn_ptr(env: &mut Env) { **env.x += 5; }