code: def get(self, key):
          
          mice = super().get(key)
  
          if mice is not None:  # Hit
              return mice
  
          # Try and get the key from the parent cache.
          if self.parent_subsystem_hash:
              parent_key = key.replace(str(self.subsystem_hash),
                                       str(self.parent_subsystem_hash), 1)
              mice = super().get(parent_key)
  
              if mice is not None and not mice.damaged_by_cut(self.subsystem):
                  return mice
  
          return None
docs: Get a value from the cache.
  
          If the |MICE| cannot be found in this cache, try and find it in the
          parent cache.