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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 _build(self, parent_cache):
 """Build the initial cache from the parent. Only include the |MICE| which are unaffected by the subsystem cut. A |MICE| is affected if either the cut splits the mechanism or splits the connections between the purview and mechanism """

        for key, mice in parent_cache.cache.items():
            if not mice.damaged_by_cut(self.subsystem):
                self.cache[key] = mice