docs: def validate_line_list(dist, attr, value):
      """
      Validate that the value is compatible
      """
  
      # does not work as reliably in Python 2.
      if isinstance(value, str):
          value = value.split()
      value = list(value)
  
      try:
          check = (' '.join(value)).split()
          if check == value:
              return True
      except Exception:
          pass
      raise DistutilsSetupError("%r must be a list of valid identifiers" % attr)