问题 Case 1: "{arg1} {arg2}".format (10, 20) It will give KeyError: 'arg1' because I didn't pass the named arguments. Case 2: "{arg1} {arg2}".format(arg1 = 10, arg2 = 20) Now it will work properly because I passed the named arguments. And it prints '10 20' Case 3: And, If I pass wrong name it will show KeyError: 'arg1' "{arg1} {arg2}".format(wrong = 10, arg2 = 20) But, Case 4: If I pass the named arguments in wrong order "{arg1} {arg2}".format(arg2 = 10, arg1 = 20) It works... and it prints '20 10