The ornamental design for the lamp, as shown and described.
FIG. 1 is an oblique front-left-top view of a lamp according to this disclosure.
FIG. 2 is an orthogonal front view of the lamp of FIG. 1.
FIG. 3 is an orthogonal rear view of the lamp of FIG. 1.
FIG. 4 is an orthogonal right view of the lamp of FIG. 1.
FIG. 5 is an orthogonal left view of the lamp of FIG. 1.
FIG. 6 is an orthogonal top view of the lamp of FIG. 1.
FIG. 7 is an orthogonal bottom view of the lamp of FIG. 1; and,
FIG. 8 is an oblique rear-left-bottom view of the lamp of FIG. 1.
The broken lines shown in the drawings are provided to show visible environmental structure, namely, fastening hardware, helmet ear holes, bat grip material, electrical lighting system components, ball stitching, and base stand feet, which form no part of the claimed design.