The ornamental design for a multi-sided whistle, as shown and described.
FIG. 1 is a top front perspective view of the multi-sided whistle showing my new design;
FIG. 2 is a right elevation view thereof;
FIG. 3 is a left elevation view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a rear elevation view thereof;
FIG. 6 is a top elevation view thereof; and,
FIG. 7 is a bottom elevation view thereof.
The dash-dash broken lines shown in the drawings illustrate portions of the article that form no part of the claimed design, it being understood that the surface which lies beneath the broken lines that cross over the solid line claim is part of the claimed design.
The article is shown with a symbolic break in length, depicted by dot-dash broken lines. The appearance of any portion of the article between the break lines forms no part of the claimed design.