docs: def include_before(predicate, num, iterative):
      """
      Return elements in `iterative` including `num`-before elements.
  
      >>> list(include_before(lambda x: x == 'd', 2, 'abcded'))
      ['b', 'c', 'd', 'e', 'd']
  
      """
      (it0, it1) = itertools.tee(iterative)
      ps = _backward_shifted_predicate(predicate, num, it1)
      return (e for (e, p) in zip(it0, ps) if p)