requests是python的第三方库，号称：
Requests: HTTP for Humans
中文快速教程在这：http://cn.python-requests.org/zh_CN/latest/
看完之后有点迷惑，不知道怎么用，看了一下源码，发现
#官冈文档中第一条就是
>>> r = requests.get(‘https://github.com/timeline.json‘)
>>> r = requests.put("http://httpbin.org/put")
>>> r = requests.delete("http://httpbin.org/delete")
>>> r = requests.head("http://httpbin.org/get")
>>> r = requests.options("http://httpbin.org/get")
#实际定义是（在api.py中）：
def request(method, url, **kwargs):
def get(url, **kwargs):
...code goes here...
return request(‘get‘, url, **kwargs):
其他几个函数也是一样的调用requests（）
其中requests函数的参数说明：
"""Constructs and sends a :class:`Request <Request>`.
Returns :class:`Response <Response>` object.
:param method: method for the new :class:`Request` object.
:param url: URL for the new :class:`Request` object.
:param params: (optional) Dictionary or bytes to be sent in the query string for the :class:`Request`.
:param data: (optional) Dictionary, bytes, or file-like object to send in the body of the :class:`Request`.
:param json: (optional) json data to send in the body of the :class:`Request`.
:param headers: (optional) Dictionary of HTTP Headers to send with the :class:`Request`.
:param cookies: (optional) Dict or CookieJar object to send with the :class:`Request`.
:param files: (optional) Dictionary of ``‘name‘: file-like-objects`` (or ``{‘name‘: (‘filename‘, fileobj)}``) for multipart encoding upload.
:param auth: (optional) Auth tuple to enable Basic/Digest/Custom HTTP Auth.
:param timeout: (optional) How long to wait for the server to send data before giving up, as a float, or a (`connect timeout, read timeout <user/advanced.html#timeouts>`_) tuple.
:type timeout: float or tuple
:param allow_redirects: (optional) Boolean. Set to True if POST/PUT/DELETE redirect following is allowed.
:type allow_redirects: bool
:param proxies: (optional) Dictionary mapping protocol to the URL of the proxy.
:param verify: (optional) if ``True``, the SSL cert will be verified. A CA_BUNDLE path can also be provided.
:param stream: (optional) if ``False``, the response content will be immediately downloaded.
:param cert: (optional) if String, path to ssl client cert file (.pem). If Tuple, (‘cert‘, ‘key‘) pair.
"""
requests函数使用了关键字参数（**kwargs）：关键字参数允许你传入0个或任意个含参数名的参数，这些关键字参数在函数内部自动组装为一个dict。 在Python中定义函数，可以用必选参数、默认参数、可变参数和关键字参数，这4种参数都可以一起使用，或者只用其中某些，但是请注意，参数定义的顺序必须是：必选参数、默认参数、可变参数和关键字参数。