Car remote

I recently saw a distraught young lady weeping beside her car. "Do you need some help?" I asked.. She replied, "I knew I should have replaced the battery to this remote door un-locker. Now I can’t get into my car. Do you think they (pointing to a distant convenience store) would have a battery to fit this?" "Hmmm, I dunno. Do you have an alarm, too?" I asked. "No, just this remote thingy," she answered, handing it and the car keys to me. As I took the key and manually unlocked the door, I replied, "Why don’t you drive over there and check about the batteries. It’s a long walk."