遍历列表，连续10个位置的类型不同

有若干类型的数据组成的列表，按照分组对列表中的数据重新排列。要求连续10个元素的分组不同。

item1 = [("a1",1) for _ in range(20)]
item2 = [("a2",2) for _ in range(20)]
item3 = [("a3",3) for _ in range(20)]
item4 = [("a4",4) for _ in range(20)]
item5 = [("a5",5) for _ in range(20)]
item6 = [("a6",6) for _ in range(20)]
item7 = [("a7",7) for _ in range(20)]
item8 = [("a8",8) for _ in range(20)]
item9 = [("a9",9) for _ in range(20)]
item10 = [("a10",10) for _ in range(20)]
item11 = [("a11",11) for _ in range(20)]
all_item = item1 + item2 + item3 + item4 + item5 + item6 + item7 + item8 + item9 + item10 + item11


from collections import MutableSequence
class MyList(MutableSequence):
    """A container for manipulating lists of hosts
        保证列表中只有10个元素
    """

    def __init__(self, data=None):
        """Initialize the class"""
        super(MyList, self).__init__()
        if (data is not None):
            self._list = list(data)
        else:
            self._list = list()

    def __len__(self):
        """List length"""
        return len(self._list)

    def __getitem__(self, ii):
        """Get a list item"""
        return self._list[ii]

    def __delitem__(self, ii):
        """Delete an item"""
        del self._list[ii]

    def __setitem__(self, ii, val):
        # optional: self._acl_check(val)
        self._list[ii] = val

    def __str__(self):
        return str(self._list)

    def insert(self, ii, val):
        # optional: self._acl_check(val)

        self._list.insert(ii, val)

    def append(self, val):
        if len(self._list) >= 9:
            self._list.pop(0)
            self._list.insert(len(self._list), val)
        else:
            self.insert(len(self._list), val)

i = 0
tag = 0
res = []
mylist = MyList()
while len(res)<=100:
    if i >=10 and tag >= 10:
        i = 0
        tag = 0

    temp = all_item[i]
    v = temp[0]
    c = temp[1]
    if c not in mylist:
        mylist.append(c)
        res.append(v)
        all_item.pop(i)
        tag += 1
    else:
        i += 1
print(res)
print(all_item)