一、定义
OrderedDict是对字典的补充，它记住了字典元素的添加顺序。
eg：

二、OrderedDict相关方法
def clear(self): # real signature unknown; restored from __doc__
    """ 
　　　　od.clear() -> None.  Remove all items from od. 
　　　　清除有序字典中的元素
　　"""
    pass
eg：

def copy(self): # real signature unknown; restored from __doc__
    """ 
　　　　od.copy() -> a shallow copy of od 
　　　　有序字典的浅拷贝
　　"""
    pass



def items(self, *args, **kwargs): # real signature unknown
    取有序字典的元素
　　 pass

def keys(self, *args, **kwargs): # real signature unknown
　　取key
    pass

def move_to_end(self, *args, **kwargs): # real signature unknown
    """
    Move an existing element to the end (or beginning if last==False).
    
            Raises KeyError if the element does not exist.
            When last=True, acts like a fast version of self[key]=self.pop(key).
　　把指定的元素放到尾部
    """
    pass
eg：

def pop(self, k, d=None): # real signature unknown; restored from __doc__
    """
    od.pop(k[,d]) -> v, remove specified key and return the corresponding
            value.  If key is not found, d is returned if given, otherwise KeyError
            is raised.
　　弹出指定的key
    """
    pass
eg：

def popitem(self): # real signature unknown; restored from __doc__
    """
    od.popitem() -> (k, v), return and remove a (key, value) pair.
            Pairs are returned in LIFO order if last is true or FIFO order if false.
　　从尾部开始弹出
    """
    pass
eg：

def setdefault(self, k, d=None): # real signature unknown; restored from __doc__
    """ 
　　　　od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od 
　　　　设置默认值
　　"""
    pass

def update(self, *args, **kwargs): # real signature unknown
    pass

def values(self, *args, **kwargs): # real signature unknown
    pass

python之collections之有序字典（OrderedDict）