關鍵字參數必須跟隨在位置參數后面! 因為python函數在解析參數時, 是按照順序來的, 位置參數是必須先滿足, 才能考慮其他可變參數.，否則報錯如下：
In [74]: print(s1.format(name='jenkins',"good","kg",a='python'))
File "<ipython-input-74-64057fd78193>", line 1
print(s1.format(name='jenkins',"good","kg",a='python'))
^
SyntaxError: positional argument follows keyword argument
場景：
In [79]: s1=('{name} is {}, he is 100{}, he love is {a}')
錯誤做法：
In [76]: print(s1.format(name='jenkins',a='python','good','kg'))
File "<ipython-input-76-25b0eb5fd5a0>", line 1
print(s1.format(name='jenkins',a='python','good','kg'))
^
SyntaxError: positional argument follows keyword argument
正確做法：
In [78]: print(s1.format("good","kg",a='python',name='jenins'))
jenins is good, he is 100kg, he love is python
意思就是說先寫關鍵字，關鍵字寫完之后，再寫賦值，賦值跟在關鍵字之后