class_docstr: A ZipFile subclass that ensures that implied directories
  are always included in the namelist.
code: def _name_set(self):
      return set(self.namelist())
  
imports: import io
  import posixpath
  import zipfile
  import itertools
  import contextlib
  import sys
  import pathlib
label_desc: Use image node_id 3 for calling the CompleteDirs obj's underlying member method code with example usage: obj._name_set() and returns: set