• 调用help函数，可以看到一个函数或者方法的字符串文档。

In [1]: import requests

In [2]: help(requests.get)

Help on function get in module requests.api:

get(url, params=None, **kwargs)
    Sends a GET request.

    :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 \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response

• 使用dir可以查看模块或对象都有那些方法。

In [3]: dir(requests)
Out[3]:
['ConnectionError',
 'HTTPError',
 'compat',
 'cookies',
 'delete',
 'exceptions',
 'get',
 'head',
 'hooks',
  ...

• 使用ipython+?查看

In [4]: requests.get?
Type:        function
String form: <function get at 0x10e6c35f0>
File:        /Library/Python/2.7/site-packages/requests/api.py
Definition:  requests.get(url, params=None, **kwargs)
Docstring:
Sends a GET request.

: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 \*\*kwargs: Optional arguments that ``request`` takes.
:return: :class:`Response <Response>` object
:rtype: requests.Response

• 使用pydoc查看字符串文档

☁  ~  python -m pydoc requests

Help on package requests:

NAME
    requests

FILE
    /Library/Python/2.7/site-packages/requests/__init__.py

DESCRIPTION
    requests HTTP library
    
    Requests is an HTTP library, written in Python, for human beings. Basic GET
    usage:

       >>> import requests
       >>> r = requests.get('https://www.python.org')
       >>> r.status_code
       200
       >>> 'Python is a programming language' in r.content
       True

很多第三方库, 都有他们自己的官网, 例如requests库, jinja2库等等. 所以如果你想用的库,刚好有他们的官网, 可以上通过搜索他们的官网上去学习, 但是如果很不幸没有, 那只能通过别人的博客或者分享去学习, 如果等基础到一定程度, 可以去直接看他们模块的源码, 从中找到你需要的东西