The ornamental design for a flexible-shaft lamp, as shown and described.
FIG. 1 is a front, right-side perspective view of a flexible-shaft lamp showing my new design with an erect shaft, the top of the lamp housing being flat, the bottom, forming no part of the design and the left side elevational view being mirror symmetrical to the right side view;
FIG. 2 is a rear right-side perspective view thereof with the flexible shaft in another orientation;
FIG. 3 is a left side perspective view thereof with the flexible shaft in yet another position;
FIG. 4 is a side elevational view of FIG. 1, the opposite side being a mirror image; and,