We claim the ornamental design for a knife, as shown and described.
FIG. 1 is a right side view of a knife, showing our new design;
FIG. 2 is a bottom view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a rear view thereof;
FIG. 6 is a front view thereof;
FIG. 7 is a right perspective view thereof;
FIG. 8 is a left perspective view thereof;
FIG. 9 is an exploded right perspective view thereof; and,
FIG. 10 is an exploded left perspective view thereof.
The dash-dot-dash broken line immediately adjacent to the shaded area represents an unclaimed boundary of the claimed design. The remainder of the broken lines are provided for environmental purposes only and form no part of the claimed design.