I claim the ornamental design for a knife, as shown and described.
FIG. 1 is a perspective view of the knife depicting portions of the top, right, and rear sides of the knife;
FIG. 2 is a perspective view depicting portions of the bottom, left, and front sides of the knife;
FIG. 3 is a bottom plan view of the knife;
FIG. 4 is a top plan view of the knife;
FIG. 5 is a right side elevational view of the knife, the left elevational view being a mirror image thereof; and,
FIG. 6 is a front side elevational view of the knife, the rear side elevational view being a mirror image thereof.
The holes in the blade of the knife, and the fasteners affixing the blade to the knife handle, all depicted in broken lines, are not part of the claimed design.