old_contents: from __future__ import print_function
  from .core import columnize
  import os
  
  __all__ = ['show_attrs', 'show_files']
  
  def show_attrs(obj):
      print(columnize(dir(obj), sort_items=True))
  
  def show_files(path='.'):
      print(columnize(os.listdir(path), sort_items=True))
  
new_contents: from __future__ import print_function
  from .core import columnize
  import os
  
  __all__ = ['show_attrs', 'show_files']
  
  def show_attrs(obj):
      print(columnize(dir(obj), sort_items=True))
  
  def show_files(path='.', hide_dotted=False):
      filenames = os.listdir(path)
      if hide_dotted:
          filenames = [fn for fn in filenames if not fn.startswith('.')]
      print(columnize(filenames, sort_items=True))
  
subject: Add `hide_dotted`-option to `show_files()`.