<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def resize_volume(self, size):
 """Changes the size of the volume for this instance."""

        curr_size = self.volume.size
        if size <= curr_size:
            raise exc.InvalidVolumeResize("The new volume size must be larger "
                    "than the current volume size of '%s'." % curr_size)
        body = {"volume": {"size": size}}
        self.manager.action(self, "resize", body=body)