code: def compact(self):
          
  
          saved_length = 0
          to_remove = []
          for i, entry in enumerate(self.entries):
              if not entry.valid:
                  to_remove.append(i)
                  saved_length += entry.data_space()
  
          for i in reversed(to_remove):
              del self.entries[i]
  
          self.data_index -= saved_length
docs: Remove all invalid config entries.