That product already exists, a blind friend of mine has one and freaks out his neighbours with it. I was visiting him one day and he'd used it for a walk aroun

That product already exists, a blind friend of mine has one and freaks out his neighbours with it. I was visiting him one day and he'd used it for a walk around around the block and his neighbour asked him how he "knew where all the cars where" and he responded "well, I ring Mary down the road and she describes the entire block to me and then I memorize it." This guy nodded his head as if that made sense and left and then my friend promptly burst into laughter and showed me his secret.