The ornamental design for a flask and cap, as shown and described.
FIG. 1 is a top. front perspective view of a flask and cap showing our new design;
FIG. 2 is a front elevation view thereof, the rear elevation view being a mirror image;
FIG. 3 is a left side elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a top, front perspective view of a second embodiment of a flask and cap showing our new design;
FIG. 7 is a front elevation view thereof, the rear elevation view being a mirror image;
FIG. 8 is a left side elevation view thereof;
FIG. 9 is a right side elevation view thereof; and,
FIG. 10 is a top plan view thereof.
The broken lines in the drawings showing the details on the cap and the bottom surface of the flask illustrate the portions of the design that form no part of the claim.