Parking at the Newtonville post office yesterday at noon was non-existent. The only open post office in town, the post office offered both mailing and passport services and it always closes at one (on Saturdays). Weather at zero degrees with a wind chill factor of you don't want to know and no parking lot within 5 minutes walking distance . . . All on-street (metered) parking spaces full. . . So what to do? Marash Girl remembered her days living on Beacon Hill when there, too, there were never any on street parking spaces available, but those days taught her to follow the keys. Follow the keys, you ask? Here's the trick. When there is no parking, empty spaces will be taken before you can blink an eye, and not by you. So Marash Girl always watches for a pedestrian with keys in his/her hands, and she follows those keys. Invariably, the keys will lead to a soon to be parking space, yours for the taking!