docs: def exponential_size_change(Nstart, Nstop, time):
      """
      Generate a list of population sizes
      according to exponential size_change model
  
      :param Nstart: population size at onset of size change
      :param Nstop: Population size to reach at end of size change
      :param time: Time (in generations) to get from Nstart to Nstop
  
      :return: A list of integers representing population size over time.
  
      .. versionadded:: 0.1.1
      """
      if time < 1:
          raise RuntimeError("time must be >= 1")
      if Nstart < 1 or Nstop < 1:
          raise RuntimeError("Nstart and Nstop must both be >= 1")
      G = math.exp((math.log(Nstop) - math.log(Nstart))/time)
      rv = []
      for i in range(time):
          rv.append(round(Nstart*pow(G, i+1)))
      return rv