FIG. 1 is a perspective view of a flask showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a left side elevation view thereof, the right side elevation view being a mirror image;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a perspective view thereof shown without the closing cap for a clear disclosure of the underlying parts;
FIG. 7 is a front elevation view thereof;
FIG. 8 is a left side elevation view thereof, the right side elevation view being a mirror image;
FIG. 9 is a top plan view thereof;
FIG. 10 is a bottom plan view thereof;
FIG. 11 is a perspective view of a second embodiment of a flask showing our new design;
FIG. 12 is a front elevation view thereof;
FIG. 13 is a left side elevation view thereof, the right side elevation view being a mirror image;
FIG. 14 is a top plan view thereof;
FIG. 15 is a bottom plan view thereof;
FIG. 16 is a perspective view of a third embodiment of a flask showing our new design;
FIG. 17 is a front elevation view thereof;
FIG. 18 is a left side elevation view thereof, the right side elevation view being a mirror image;
FIG. 19 is a top plan view thereof; and,
FIG. 20 is a bottom plan view thereof.
The appearance within the unshaded region of FIGS. 5 and 10 forms no part of the claimed design.