The ornamental design for a scarf, as shown and described.
FIG. 1 is a front perspective view of a scarf according to an embodiment of the present design;
FIG. 2 is a front elevation view of the scarf shown in FIG. 1;
FIG. 3 is a back elevation view of the scarf shown in FIG. 1;
FIG. 4 is a left side elevation view of the scarf shown in FIG. 1;
FIG. 5 is a right side elevation view of the scarf shown in FIG. 1;
FIG. 6 is a bottom plan view of the scarf shown in FIG. 1; and,
FIG. 7 is a top plan view of the scarf shown in FIG. 1.
The broken lines shown in FIGS. 1-7 illustrate environmental subject matter and form no part of the claimed design. The broken lines which bisect the claimed design indicate that any portion of the article beyond what is shown forms no part of the claimed design. The dot-dash-dot lines shown in the drawings illustrate a boundary and form no part of the claimed design.