class xor_doublylinked_list:
    def __init__(self, data, head=None, tail=None):
        self.data = data

    def push_back(element):


class xor_doublylinked_node:
    def __init__(self, data, both=None): # both is of type pointer to an xor of prev and next xor_doublylinked_nodes
        self.data = data
