docs: def grep(rootdir, searched):
      "grep -l <searched>"
      to_inspect = []
      for root, dirs, files in os.walk(rootdir):
          for _file in files:
              if _file.endswith('.rst'):
                  to_inspect.append(join(root, _file))
  
      to_check = ((_file, open(_file, 'r').read()) for _file in to_inspect)
      to_check = filter(lambda item: searched in item[1], to_check)
      to_check = map(lambda item: item[0], to_check)
      return to_check