docs: def listify(value):
      """
      Wrap the given value into a list, with the below provisions:
  
      * If the value is a list or a tuple, it's coerced into a new list.
      * If the value is None, an empty list is returned.
      * Otherwise, a single-element list is returned, containing the value.
  
      :param value: A value.
      :return: a list!
      :rtype: list
      """
      if value is None:
          return []
      if isinstance(value, (list, tuple)):
          return list(value)
      return [value]