The ornamental design for a lamp, as shown and described.
FIG. 1 is a perspective view of a lamp according to the present invention.
FIG. 2 is a side view of the lamp of FIG. 1; and,
FIG. 3 is a top view of the lamp of FIG. 1.
The break line depicted in FIGS. 1 and 2 denotes the lamp may contain additional repetitive, symmetrical sections, identical to those disclosed in the Figures.
The broken line of a cord and plug in FIGS. 1-3, inclusive, is for environmental purposes only and forms no part of the claimed design.