code: def _order_as_range(order):
      
      order = order.split('-')
      order = [int(o) for o in order]
      if len(order) > 1:
          order = range(order[0], (order[-1] + 1))
      return order
docs: Convert a hyphenated string representing order for derivative or
      exponential terms into a range object that can be passed as input to the
      appropriate expansion function.