The ornamental design for a cooler, as shown and described.
FIG. 1 is a perspective top front view of a cooler with the lid in a closed position, showing my new design;
FIG. 2 is a perspective top and front view of the cooler with the lid shown in an open position and the two (2) interior inserts shown exploded and adjacent to the cooler;
FIG. 3 is a left-side elevation view thereof;
FIG. 4 is a right-side elevation view thereof;
FIG. 5 is an enlarged front side elevation view thereof;
FIG. 6 is a rear side elevation view thereof;
FIG. 7 is a top side plan view thereof;
FIG. 8 is a bottom side plan view thereof; and,
FIG. 9 is a perspective top front view of a cooler with the lid in an opened position and two (2) inserts installed.
The broken lines detailed in FIG. 5 are intended to illustrate a boundary area and form no part of the claimed.