interactive python(2) http://www.codeskulptor.org/#user18_xMNnLS4eSr_0.py timer的使用 http://www.codeskulptor.org/#user18_Gu9Q08s2US_0.py draw_circle http://www.codeskulptor.org/#user18_xQk8pGROqn_0.py stopclock http://www.codeskulptor.org/#user18_kN9oIkVZtv_2.py