The ornamental design for a bag, as shown and described.
FIG. 1 is a perspective view taken from the front, right side and top side of the bag of the present design, shown with its top opening in a closed position, in accordance with the present design.
FIG. 2 is another perspective view taken from the front, right side and top side of the bag of FIG. 1, shown with its top opening in an open position and the straps in a relaxed configuration, in accordance with an aspect the present design.
FIG. 3 is a front elevation view of the bag of FIG. 1.
FIG. 4 is a rear elevation view of the bag of FIG. 1.
FIG. 5 is a right side elevation view of the bag of FIG. 1.
FIG. 6 is a left side elevation view of the bag of FIG. 1.
FIG. 7 is a top plan view of the bag of FIG. 1; and,
FIG. 8 is a bottom plan view of the bag of FIG. 1.
The dash-dash broken lines shown represent stitching and form part of the claimed design. Elements drawn in broken short/long dash lines are included for illustrating portions of the bag, and form no part of the claimed design.