The ornamental design for a stylus, as shown and described.
FIG. 1 is a perspective view from the lower right front of the stylus;
FIG. 2 is a front view of the stylus;
FIG. 3 is a rear view of the stylus;
FIG. 4 is a left side view of the stylus;
FIG. 5 is a right side view of the stylus;
FIG. 6 is a top view of the stylus;
FIG. 7 is a bottom view of the stylus; and,
FIG. 8 is a perspective view from the upper left rear of the stylus, shown in use in a typical environment.
The broken lines shown in the drawings illustrate unclaimed portions of the design and/or environmental structure and form no part of the claimed design.