The ornamental design for a valve, as shown and described.
FIG. 1 is a front perspective view of a valve showing my new design.
FIG. 2 is a left side elevation view thereof.
FIG. 3 is a right side elevation view thereof.
FIG. 4 is a front elevation view thereof.
FIG. 5 is a rear elevation view thereof.
FIG. 6 is a top plan view thereof.
FIG. 7 is a bottom plan view thereof.
FIG. 8 is a perspective-sectional view of the inner surface thereof along section 8-8 in FIG. 1.
FIG. 9 is a front-section elevation view of the inner front side of FIG. 8, the rear-section elevation view being a mirror image thereof; and,
FIG. 10 is a right side-section elevation view of the inner right side surface thereof along section 10-10 in FIG. 1, the left side-section elevation view being a mirror image thereof.
The dash-dash lining in the figures indicate portions of the valve that form no part of the claimed design. The dash-dot-dash lines indicate bounds of the claimed design; and form no part thereof.