code: def compress_dhist(dh):
      """Compress a directory history into a new one with at most 20 entries.
  
      Return a new list made from the first and last 10 elements of dhist after
      removal of duplicates.
      """
      head, tail = dh[:-10], dh[-10:]
  
      newhead = []
      done = set()
      for h in head:
          if h in done:
              continue
          newhead.append(h)
          done.add(h)
  
      return newhead + tail
  
imports: import os
  import re
  import sys
  from getopt import getopt, GetoptError
  from traitlets.config.configurable import Configurable
  from .None import oinspect
  from .error import UsageError
  from .inputtransformer2 import ESC_MAGIC, ESC_MAGIC2
  from ..utils.ipstruct import Struct
  from ..utils.process import arg_split
  from ..utils.text import dedent
  from traitlets import Bool, Dict, Instance, observe
  from logging import error
label_desc: Use image node_id 2 for calling a global function with example usage: compress_dhist(dh) and returns: unknown