The ornamental design for a lamp, as shown and described.
FIG. 1 is a first perspective view of a lamp showing my new design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof;
FIG. 8 is a bottom view thereof;
FIG. 9 is an enlarged view of the selected portion 9 in FIG. 1; and,
FIG. 10 is an enlarged view of the selected portion 10 in FIG. 2.
The broken lines shown in the drawings depict portions of the lamp that form no part of the claimed design. The dash-dot-dash lines encircling the enlarged views in FIGS. 1-2, 9-10 are for annotative purposes only and form no part of the claim thereof. The lamp is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design.