The ornamental design for a handbag, as shown and described.
FIG. 1 is a front perspective view of a handbag showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a right side elevational view, the left side being a mirror image thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The wide elongated ring shown in FIGS. 1, 2, and 5, on the front flap portion of the handbag and forming a part of the claimed design is a registered trademark of J. Choo Limited.