The ornamental design for a bag, as shown and described.
FIG. 1 is a top front perspective view of a bag showing the claimed design in an open configuration;
FIG. 2 is a front view thereof in a closed configuration;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof, the right side view being a mirror image thereof;
FIG. 5 is a top view thereof; and,
FIG. 6 is a bottom view thereof.
The dashed broken lines in the figures show environment, which forms no part of the claimed design.
The dot-dash broken lines and the portions between pairs of dot-dash lines that are broken away show the bag has no specific length and form no part of the claimed design. For ease of illustration, the dot-dash broken lines do not appear in FIG. 1.
The gray-shaded portions in the figures show contrasting appearance.