Flask

FIG. 1 is a top perspective view of a flask showing our new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a front elevation view thereof, wherein a rear elevation view thereof is a mirror image of the front elevation view;

FIG. 4 is a left-side elevation view thereof, wherein a right-side elevation view thereof is a mirror image of the left-side elevation view;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

Broken lines in the figures illustrate portions of the flask that form no part of the claimed design.