class_docstr: A ZipFile subclass that ensures that implied directories
  are always included in the namelist.
code: def _implied_dirs(names):
      parents = itertools.chain.from_iterable(map(_parents, names))
      as_dirs = (p + posixpath.sep for p in parents)
      return _dedupe(_difference(as_dirs, names))
  
imports: import io
  import posixpath
  import zipfile
  import itertools
  import contextlib
  import sys
  import pathlib
label_desc: Use image node_id 1 for calling the CompleteDirs obj's underlying member method code with example usage: obj._implied_dirs(names) and returns: _dedupe