code: def close(self):
      additional_bits = 8 - len(self.buffer)
      if (
          additional_bits != 8
      ):  # buffer is empty, no need to append extra "0"
          self.write_bits("0" * additional_bits)
          self._save_information_about_additional_bits(additional_bits)
  
imports: from collections import defaultdict, deque
  import heapq
label_desc: Use image node_id 7 for calling the HuffmanWriter obj's underlying member method code with example usage: obj.close() without return types