The ornamental design for keyboard, as shown and described.
FIG. 1 is a front perspective view of a keyboard according to a first embodiment of our new design, the keyboard including function keys on the right side of the keyboard, the function keys having symbols which are the same color as the function keys;
FIG. 2 is a front perspective view of a keyboard according to a second embodiment of our new design, the keyboard including function keys on the right side of the keyboard, the function keys having dark colored symbols; and,
FIG. 3 is a front perspective view of a keyboard according to a third embodiment of our new design, the keyboard including function keys on the right side of the keyboard, the function keys having lightly colored symbols.
Except for the differences in the function keys described above, the shapes of the keyboards of the embodiments of FIGS. 1–3 are identical.