We claim the ornamental design for a knife, as shown and described.
FIG. 1 is a rear top perspective view of the claimed design.
FIG. 2 is a rear bottom perspective view thereof.
FIG. 3 is a left side view thereof.
FIG. 4 is a right side view thereof.
FIG. 5 is a front view thereof.
FIG. 6 is a rear view thereof.
FIG. 7 is top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines in the drawings are for illustrative purposes only and form no part of the claimed design. Broken lines formed by equal length dashes show unclaimed portions of the design. Broken lines formed of unequal length dashes (i.e., dash-dot) show boundaries between claimed and unclaimed portions of the design.