The ornamental design for a lamp, as shown and described.
FIG. 1 is a perspective view of a lamp showing my new design;
FIG. 2 is a front view thereof; and,
FIG. 3 is a top view thereof.
The broken lines in FIGS. 1-3 are shown for environmental purposes only and
form no part of the claimed design. The dotted lines shown in FIGS. 1 and
3 represent peripheries of the claimed design and form no part thereof.
The lamp standard is shown broken away to indicate indeterminate length.