若在python2檔案中硬編碼一箇中文字串（python2檔案編碼設為utf-8），
其型別為一個str變數，可以使用decode('utf-8')方法將其轉化為unicode變數

a = '測試'
type(a)
Out[1]: str
a.decode('utf-8')
Out[2]: u'\u6d4b\u8bd5'
a.encode('utf-8')
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/IPython/core/interactiveshell.py", line 2882
 
, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-7-e6028649de51>", line 1, in <module>
    a.encode('utf-8')
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe6 in position 0: ordinal not in range(128)

python中字串有以下轉化關係

     decode()             encode()
 

str ----------> unicode -----------> str