We claim the ornamental design for a lamp, as shown and described.
FIG. 1 is a perspective view of a lamp showing our new design;
FIG. 2 is a left view thereof;
FIG. 3 is a right view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a rear view thereof
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the drawings represent portions of the lamp that form no part of the claimed design. Elements of the lamp have been broken away in all of the figures to indicate that no particular length is claimed, it being understood that the design repeats uniformly throughout its length.