Exercise 4.1.18: Generalize the pond function so that it takes as parameters the number of years, the initial population, the harvest, and the annual growth rate (which in the book was 8% always). Your function should return the final population after that many years. Do not print anything. Your answer should be in the form of an integer, so use the int() command at the end. Assume rate is a number between 0 and 1.