'''
1 Execution sequence with ASCII. 0~9,A~Z,a~z
2 use the function that suite to assign execution sequence
as follow:
suite=unittest.TestSuite()
suite.addTest(TestAdd('test_add1')) #first
suite.addTest(TestAdd('test_add2')) #second
suite.addTest(TestSub('test_asb1')) #thirdly
suite.addTest(TestSub('test_sub2')) #fourthly
# operational the test set
runner=unittest.TextTestRunner()
runner.run(suite)
'''
