We claim the ornamental design for a light bulb, as shown and described.
FIG. 1 is a top perspective view showing an embodiment of our design for a light bulb. In this view, as well is in other views for this embodiment, seam lines and a base portion of the bulb are shown in dotted lines because these portions are not part of the claim for this embodiment.
FIG. 2 is a bottom perspective view of the embodiment of our design shown in FIG. 1.
FIG. 3 is a top view of the embodiment of our design shown in FIG. 1.
FIG. 4 is a bottom view of the embodiment of our design shown in FIG. 1.
FIG. 5 is a side view of the embodiment of our design shown in FIG. 1.
FIG. 6 is another side view of the embodiment of our design as shown in FIG. 1.
FIG. 7 is another side view of the embodiment of our design as shown in FIG. 1; and,
FIG. 8 is another side view of the embodiment of our design as shown in FIG. 1.