The ornamental design for a lamp, as shown and described.
FIG. 1 is a front and top perspective view of a lamp, showing my new design;
FIG. 2 is a rear and bottom perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a right side elevation view thereof;
FIG. 7 is a top plan view thereof;
FIG. 8 is a bottom plan view thereof;
FIG. 9 is an enlarged perspective view of detail “9” identified in FIG. 1; and,
FIG. 10 is an enlarged perspective view of detail “10” identified in FIG. 2.
The dashed lines in the figures illustrate portions of the lamp that form no part of the claimed design. The dash dot dash lines in FIGS. 1, 2, 9 and 10 are for the purpose of illustrating the enlarged views indicators and form no part of the claimed design.