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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def track_size(self, ts, sizer):
 """ Store timestamp and current size for later evaluation. The 'sizer' is a stateful sizing facility that excludes other tracked objects. """

        obj = self.ref()
        self.snapshots.append(
            (ts, sizer.asized(obj, detail=self._resolution_level))
        )
        if obj is not None:
            self.repr = safe_repr(obj, clip=128)