What is claimed is the ornamental design for a lamp, as shown and described.
FIG. 1 is a top perspective view of the lamp;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a cross-sectional view thereof, taken along the line A-A in FIG. 6.
The portions of the lamp shown in broken lines form no part of the claimed design. The lamp is shown with symbolic breaks in its length. The appearance of any portion of the article between the break lines form no part of the claimed design.