implementation of `itertools.tee()` using one linked list instead of n deques

tee.py

import collections

class LinkedList:
    def __init__(self, value, tail=None):
        self.value = value
        self.tail = tail

def tee(iterable, n=2):
    it = iter(iterable)
    empty = LinkedList(None)
    positions = [empty] * n
    def gen(i):
        while True:
            if not positions[i].tail:                   # when local position is at the end of the list
                newval = next(it)                       # fetch a new value and
                positions[i].tail = LinkedList(newval)  # add it to the list
            positions[i] = positions[i].tail            # advance local position in the list
            yield positions[i].value
    return tuple(gen(i) for i in range(n))

There is no need to create a list of positions:

def tee(iterable, n=2):
    it = iter(iterable)
    empty = LinkedList(None)
    def gen():
        position = empty
        while True:
            if not position.tail:                   # when local position is at the end of the list
                newval = next(it)                   # fetch a new value and
                position.tail = LinkedList(newval)  # add it to the list
            position = position.tail                # advance local position in the list
            yield position.value
    return tuple(gen() for i in range(n))