The ornamental design for a computer, as shown and described.
FIG. 1 is a perspective view of a computer showing the new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a left side elevational view thereof; and,
FIG. 4 is an enlarged partial cross sectional view thereof taken along the lines 4-4 and 4′-4′ of FIG. 2.
Dot-dash broken lines immediately adjacent to the shade lines in the figures define the boundaries of, but not included in, the claimed design. All other broken lines are for the environment only and form no part of the claimed design.