Alternatively, in case of Python 2.x, you can use httplib.responses:
>>> import httplib
>>> httplib.responses[200]
'OK'
>>> httplib.responses[404]
'Not Found'
In Python 3.x, use http module:
In [1]: from http.client import responses
In [2]: responses[200]
Out[2]: 'OK'
In [3]: responses[404]
Out[3]: 'Not Found'