The ornamental design for a printer, as shown and described.
FIG. 1 is a front, top and right side perspective view of a printer showing my new design;
FIG. 2 is a rear, top, and left side perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a right side view thereof; and,
FIG. 7 is a left side view thereof.
The dot-dash and evenly spaced broken lines that are immediately adjacent to the shaded areas depict the bounds of the claimed design, while all other broken lines are directed to environment. The broken lines form no part of the claimed design.