The ornamental design for a lamp, as shown and described.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
1.-4. Lamp
1.1) Front;
1.2) Perspective;
1.3) Top;
1.4) Bottom;
1.5) Perspective
The areas shown in blue depict portions of the lamp that form no part of the claimed design.