The ornamental design for a stapler, as shown and described.
FIG. 1 is a top, rear, right side perspective view of a stapler showing my
new design;
FIG. 2 is a top, front, left side perspective view thereof; and
FIG. 3 is a bottom, rear, left side perspective view thereof.
Other views of my new design are as shown in corresponding Swedish Design
Application No. 89-1385, filed June 7, 1989, and incorporated herein by
reference.