The ornamental design for a zipperpull, as shown and described.
FIG. 1 is a front elevation view of a zipper pull showing my new design;
FIG. 2 is a rear elevation view thereof;
FIG. 3 is a left side elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof;
FIG. 7 is a right perspective view thereof; and,
FIG. 8 is a using status perspective view for reference.
The broken line showing of a zipper slider in FIG. 8 is included for the purpose of illustrating environmental matter and forms no part of the claimed design.