text: """
  Write a function future_value that takes three parameters
  present_value, annual_rate and years
  and returns the future value of present_value dollars invested
  at annual_rate percent interest, compounded annually for years years.
  """
  
  # Future value formula
  def future_value(present_value, annual_rate, years):
      return present_value * (1 + 0.01 * annual_rate) ** years
  
  # Tests
  def test(present_value, annual_rate, years):
      print "The future value of $" + str(present_value) + " in " + str(years),
      print "years at an annual rate of " + str(annual_rate) + "% is",
      print "$" + str(future_value(present_value, annual_rate, years)) + "."
  
  # Output
  test(1000, 7, 10)
  test(200, 4, 5)
  test(1000, 3, 20)
  
  #The future value of $1000 in 10 years at an annual rate of 7% is $1967.15135729
  #The future value of $200 in 5 years at an annual rate of 4% is $243.33058048
  #The future value of $1000 in 20 years at an annual rate of 3% is $1806.11123467