code: def _powerset(iterable):
      """
      https://docs.python.org/3/library/itertools.html#recipes
      powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)
  
      Parameters
      ----------
      iterable: any iterable
  
      Returns
      -------
      chain: a generator of the powerset of the input
      """
      s = list(iterable)
      return chain.from_iterable(
          combinations(s, r) for r in range(len(s) + 1)
      )
  
label_desc: Use image node_id 2 for calling a global function with example usage: _powerset(iterable) and returns: chain