The ornamental design for a comb, as shown and described.
FIG. 1 is a front perspective view of a comb;
FIG. 2 is a front elevation view thereof, the rear elevation view being a mirror image thereof;
FIG. 3 is a left side elevation view thereof, the right side elevation view being a mirror image thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof; and,
FIG. 6 is an enlarged detail section view of FIG. 4 taken along section 6-6.
The broken lines shown in the drawings depict a portion of a comb that forms no part of the claimed design. The dash-dot broken lines in the figures are demarcating enlarged areas and form no part of the claimed design.