We claim the ornamental design for a knife, as shown and described.
FIG. 1 is a perspective view of a knife, showing our new design;
FIG. 2 is a right side view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a back view thereof;
FIG. 6 is another right side view thereof, but shown with different broken line subject matter;
FIG. 7 is another right side view thereof, but shown with different broken line subject matter;
FIG. 8 is another right side view thereof, but shown with different broken line subject matter; and,
FIG. 9 is another right side view thereof, but shown with different broken line subject matter.
The dash-dash broken lines illustrate portions of the knife that form no part of the claimed design. The dash-dot-dot-dash broken lines represent the bounds of the claim and form no part of the claimed design.