We claim the ornamental design for a printer, as shown and described.
FIG. 1 is a front perspective view of a printer;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right view thereof;
FIG. 5 is a left view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The dash-dash broken lines in the drawings are environmental lines while the dash-dot-dash broken lines represent boundary lines, neither of which form part of the claimed design.