Using Curve objects
This test program is in the main function of curve.py.  Uncomment
out portions of the function as you implement methods in the Curve
class.  The full function graphs the function f(x) = x^3 - 15x.
def main():
  #curve = Curve()
  #print(curve)
  #x=-5
  #while x <= 5:
  #  curve.add_point(x, x**3 - 15*x)
  #  x += 0.05
  #print(curve)
  #curve.set_color("green")
  #print(curve)
  #win = GraphWin("Testing Curve class", 1000, 1000)
  #xmin = curve.get_min_x()
  #xmax = curve.get_max_x()
  #ymin = curve.get_min_y()
  #ymax = curve.get_max_y()
  #print("%.2f, %.2f, %.2f, %.2f" % (xmin,ymin,xmax,ymax))
  #win.setCoords(xmin,ymin,xmax,1.2*ymax)
  #curve.draw(win)
  #win.getMouse()
  #baseline = curve.get_baseline()
  #baseline.draw(win)
  #win.getMouse()
if __name__ == "__main__":
  main()