The ornamental design for a straw, as shown and described.
FIG. 1 is a top perspective view of a straw.
FIG. 2 is a bottom perspective view of the straw of FIG. 1.
FIG. 3 is a rear elevation view of the straw of FIG. 1.
FIG. 4 is a left side elevation view of the straw of FIG. 1.
FIG. 5 is front elevation view of the straw of FIG. 1.
FIG. 6 is a right side elevation view of the straw of FIG. 1.
FIG. 7 is a top plan view of the straw of FIG. 1; and,
FIG. 8 is a bottom plan view of the straw of FIG. 1.
The evenly spaced broken lines and the areas within them in the drawings illustrate portions of the straw that form no part of the claimed design. The dash-dot-dash-dot broken lines in the drawings represent symbolic breaks along the straw length. The break lines and the areas within them form no part of the claimed design.