Shelf

FIG. 1 is a front perspective view of a shelf;

FIG. 2 is a front elevation view of a shelf;

FIG. 3 is a rear elevation view of a shelf;

FIG. 4 is a right side view of a shelf;

FIG. 5 is a left side view of a shelf;

FIG. 6 is a top view of a shelf;

FIG. 7 is a bottom view of a shelf; and,

FIG. 8 is a rear perspective view of a shelf.

The shade lines in the Figures show contour and not surface ornamentation.

The broken lines showing portions of the design in all figures are included for the purpose of illustrating portions of the article that do not form a part of the claimed design. a