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　　"""    passeg：

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    """    passeg：

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    """    passeg：

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    """    passeg：

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