I claim the ornamental design for a flexible covering, as shown and described.
FIG. 1 shows a perspective view of a flexible covering of the present invention.
FIG. 2 shows a left side view of the flexible covering of FIG. 1.
FIG. 3 shows a top view of the flexible covering of FIG. 1.
FIG. 4 shows a bottom view of the flexible covering of FIG. 1.
FIG. 5 shows a front view of the flexible covering of FIG. 1.
FIG. 6 shows a rear view of the flexible covering of FIG. 1.
FIG. 7 shows a right side view of the flexible covering of FIG. 1.
FIG. 8 shows a perspective view of the flexible covering of FIG. 1 in an intended use; and,
FIG. 9 shows a perspective view of another environmental view of a flexible covering of the present invention.
The broken lines in the drawings illustrate unclaimed portions or the intended use environment of the flexible covering, and form no part of the claimed design.