The ornamental design for a printer, as shown and described.
FIG. 1 is a left-side perspective view of a printer;
FIG. 2 is a front view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a left-side view thereof;
FIG. 5 is a right-side view thereof;
FIG. 6 is a rear view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a right-side perspective view thereof.
The dot-dash broken lines depict the bounds of the claimed design, while all evenly spaced broken lines are directed to environment. In addition, the unshaded surface that directly adjoins the solid line edges form no part of the claimed design. The broken lines form no part of the claimed design.