I claim the ornamental design for a basket, as shown and described.
FIG. 1 is an isometric view of a basket;
FIG. 2 is another isometric view of the basket of FIG. 1;
FIG. 3 is a top plan view of the basket of FIG. 1;
FIG. 4 is a bottom view of the basket of FIG. 1;
FIG. 5 is a front elevation view of the basket of FIG. 1;
FIG. 6 is a rear elevation view of the basket of FIG. 1;
FIG. 7 is a left side elevation view of the basket of FIG. 1; and,
FIG. 8 is a right side elevation view of the basket of FIG. 1.
The even length broken lines in the figures represent portions of the article that form no part of the claimed design. The uneven length broken lines in the figures illustrate boundaries and form no part of the claimed design.