code: def iteration_length(N, start=0, step=1):
      '''Return the number of iteration steps over a list of length N,
  starting at index start, proceeding step elements at a time.
      '''
      if N < 0:
          raise ValueError('N cannot be negative')
  
      if start < 0:
          start += N
          if start < 0:
              raise ValueError('Invalid start value')
  
      if step < 0:
          step = -step
          new_N = start + 1
          if new_N > N:
              raise ValueError('Invalid parameters')
          N = new_N
          start = 0
  
      ret = int(math.ceil((N - start) / float(step)))
      return max(0, retf iteration_length(N, start=0, step=1):
      '''Return the number of iteration steps over a list of length N,
  starting at index start, proceeding step elements at a time.
      '''
      if N < 0:
          raise ValueError('N cannot be negative')
  
      if start < 0:
          start += N
          if start < 0:
              raise ValueError('Invalid start value')
  
      if step < 0:
          step = -step
          new_N = start + 1
          if new_N > N:
              raise ValueError('Invalid parameters')
          N = new_N
          start = 0
  
      ret = int(math.ceil((N - start) / float(step)))
      return max(0, ret)
docs: Return the number of iteration steps over a list of length N,
  starting at index start, proceeding step elements at a time.