Pythonで線形リスト

標準の型で入っててくれたら便利なのにー
以前も書いた気がしますけれども　ちょっと必要になったので　Pythonで線形リスト (Consリスト）を書いてメモ

from collections.abc import Iterable

class Cons( object ):

    def __init__(self,left,right):

        self.left=left

        self.right=right

    def __iter__(self):

        if isinstance(self.left,Cons):

            l= tuple(self.left.__iter__())

        else:

            l= self.left

        yield l

        if isinstance(self.right,Cons):

            for i in self.right:

                yield i

        elif  self.right is None:

            raise StopIteration

        else:

            yield self.right
    def __str__(self):

        return str(tuple(iter(self)))
class ConsList(Cons):

    def __init__(self, itr):        

        self.left=None

        self.right=None

        left=itr[0]

        if isinstance(left,Iterable):

            self.left=ConsList(left)    

        else:

            self.left=left

        right=itr[1:]

        if len(right)>0:

            self.right=ConsList(right)

        else:

            self.right=None
if __name__=="__main__":

    c=ConsList( [[1,2,3],[4,5,6],[7,8,9]])

    print(c)

    c=ConsList(range(15))

    print(c)

    c=ConsList([1,2,3])

    assert c.right.right.right is None

    assert list(c)==[1, 2, 3]

    print("done")