code: def generate_dir_rst(src_dir, target_dir, gallery_conf, seen_backrefs):
      
      if not os.path.exists(os.path.join(src_dir, 'README.txt')):
          print(80 * '_')
          print('Example directory %s does not have a README.txt file' %
                src_dir)
          print('Skipping this directory')
          print(80 * '_')
          return ""  # because string is an expected return type
  
      fhindex = open(os.path.join(src_dir, 'README.txt')).read()
      if not os.path.exists(target_dir):
          os.makedirs(target_dir)
      sorted_listdir = [fname for fname in sorted(os.listdir(src_dir))
                        if fname.endswith('.py')]
      entries_text = []
      for fname in sorted_listdir:
          amount_of_code = generate_file_rst(fname, target_dir, src_dir,
                                             gallery_conf)
          new_fname = os.path.join(src_dir, fname)
          intro = extract_intro(new_fname)
          write_backreferences(seen_backrefs, gallery_conf,
                               target_dir, fname, intro)
          this_entry = _thumbnail_div(target_dir, fname, intro) + """
  
  .. toctree::
     :hidden:
  
     /%s/%s\n""" % (target_dir, fname[:-3])
          entries_text.append((amount_of_code, this_entry))
  
      # sort to have the smallest entries in the beginning
      entries_text.sort()
  
      for _, entry_text in entries_text:
          fhindex += entry_text
  
      # clear at the end of the section
      fhindex += """.. raw:: html\n
      <div style='clear:both'></div>\n\n"""
  
      return fhindex
docs: Generate the gallery reStructuredText for an example directory