<dir，help，__doc__>查看Python帮助文档

• dir 函数查看对象的属性

# 以 list 类型为例
>>> dir(list)
['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__',
'__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__',
 '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', 
'__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 
'pop', 'remove', 'reverse', 'sort']
>>>

• __doc__ 查看对象的某个属性的帮助文档

# 查看 list 的 insert 属性
>>> print(list.insert.__doc__)
L.insert(index, object) -- insert object before index
>>>

• help 函数查看对象的某个属性的帮助文档

>>> help(list.insert)
Help on method_descriptor:

insert(...)
    L.insert(index, object) -- insert object before index

>>>