code: def add_range(self, start, stop, step=1, pad=0):
          
          assert start < stop, "please provide ordered node index ranges"
          assert step > 0
          assert pad >= 0
          assert stop - start < 1e9, "range too large"
  
          if pad > 0 and self.padding is None:
              self.padding = pad
          set.update(self, range(start, stop, step))
docs: Add a range (start, stop, step and padding length) to RangeSet.
          Like the Python built-in function range(), the last element is
          the largest start + i * step less than stop.