The shape and configuration for a cooker, as shown and described.
FIG. 1 is a perspective view of a cooker showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is an operational perspective view thereof showing that a heater illustrated in chain lines with double dots is mounted in the cooker and forms no part of the claimed design;
FIG. 9 is an operational perspective view thereof showing that another heater illustrated in chain lines with double dots is mounted in the cooker and forms no part of the claimed design; and,
FIG. 10 is an operational perspective view thereof showing that a cooking pot illustrated in chain lines with double dots is mounted on the cooker and forms no part of the claimed design;
wherein the broken lines are shown for illustrative purposes only and form no part of the claimed design.