The ornamental design for a printer, as shown and described.
FIG. 1 is a perspective view of a printer showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left elevational view thereof;
FIG. 5 is a right elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The four broken line circles shown on the side in FIGS. 1 and 5 are directed to environment. All other broken lines immediately adjacent to the shaded areas depict the bounds of the claimed design, and all broken lines within are directed to environment. The broken lines form no part of the claimed design.