We claim the ornamental design for a computer, as shown and described.
FIG. 1 is a perspective view of a computer according to our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines formed by dashes show unclaimed subject matter and form no part of the claimed design.