I claim the ornamental design of the coffee machine, as shown and described.
FIG. 1 is a front, left side isometic view of the coffee machine embodying my new design;
FIG. 2 is a front view of the coffee machine illustrated in FIG. 1, but without the coffee cup and the coffee filter that are shown in broken line in FIG. 1;
FIG. 3 is a rear view of the coffee machine;
FIG. 4 is a right side view of the coffee machine; and,
FIG. 5 is a left side view of the coffee machine.
The broken lines in the drawings are included for the purpose of illustration of a cup, filter and trademark, and form no part of the claimed design.