The ornamental design for a bag, as shown and described.
FIG. 1 is a perspective view of a bag showing my new design and having handle flaps tied and the bag partially expanded.
FIG. 2 is a front plan view of the bag shown in FIG. 1 showing my new design and having top handle flaps facing in a first direction and bottom handle flaps facing in another direction.
FIG. 3 is a front plan view of the bag shown in FIG. 2 showing my new design and having the handle flaps facing in the same direction.
FIG. 4 is a top elevation view of the bag shown in FIG. 3 showing my new design.
FIG. 5 is a bottom elevation view of the bag shown in FIG. 3 showing my new design; and,
FIG. 6 is a side elevation view of the bag shown in FIG. 1 showing my new design, the other side elevation view being a mirror image thereof.