The ornamental design for a lock, as shown and described.
FIG. 1 is a left side, top and front perspective view of the lock showing my new design and showing the lock in the “locked” position;
FIG. 2 is a top plan view thereof, the bottom plan view being a mirror image;
FIG. 3 is a front view thereof;
FIG. 4 is a left side elevational view thereof, the right side elevational view being a mirror image; and
FIG. 5 is a rear view thereof.
FIG. 6 is a top plan view of the lock showing my new design and showing the lock in the “unlocked” position, the bottom plan view being a mirror image; and,
FIG. 7 is a left side elevational view thereof, the right side elevational view being a mirror image.