The ornamental design for a stylus, as shown and described.
FIG. 1 is a perspective view of a stylus showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left view thereof;
FIG. 5 is a right view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is an exploded view thereof, as shown a stylus environment.
The broken lines in the drawings are included for the purpose of illustration and form no part of the claimed design. The dot-dash lines in the drawings define the boundary of the claim and form no part of the claimed design.