Bulb

FIG. 1 is a perspective view of a bulb showing my new design; FIG. 2 is a front elevation view thereof; FIG. 3 is a rear elevation view thereof; FIG. 4 is a left side elevation view thereof; FIG. 5 is a right side elevation view thereof; FIG. 6 is a top plan view thereof; FIG. 7 is a bottom plan view thereof; FIG. 8 is another perspective view thereof; and, FIG. 9 is a perspective view thereof, shown in a position of use. The broken lines show in the drawings illustrate portions of the bulb that form no part of the claimed design.