The ornamental design for a lampstand, as shown and described.
FIG. 1 is a perspective view of a lamp stand showing my new design;
FIG. 2 is a front elevational view thereof, the opposite end and the left
side and the right side being identical in appearence;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof; and,
FIG. 5 is a perspective view of the lamp stand, the shade being shown in
broken lines for illustrative purposes only and forming no part of the
claimed design.