Waiting for the train, linkedlist!

linkedlist.py

class Node:
    def __init__(self, value, next_reference=None):
        if not value.__hash__: hash(value)
        self.value = value
        self.next_reference = next_reference

class Linkedlist:
    def __init__(self):
        self.head = None
        self.tail = None

    def append(self, value):
        node = Node(value)
        if not self.head:
            self.head = node
            self.tail = self.head
            return self

        self.tail.next_reference = node
        self.tail = self.tail.next_reference
        return self

    def remove(self, value):
        if not self.head: return self

        if self.head.value == value:
            self.head = self.head.next_reference
            return self

        previous_node, current_node = self.head, self.head.next_reference
        while current_node and current_node.value != value:
            previous_node = current_node
            current_node = current_node.next_reference

        if not current_node: return self
        previous_node.next_reference = current_node.next_reference
        return self

    def __str__(self):
        return self._aslist().__str__()

    def _aslist(self):
        values = []
        current_node = self.head
        while current_node:
            values.append(current_node.value)
            current_node = current_node.next_reference
        return values

    def __eq__(self, other):
        if not isinstance(other, list): return False
        return self._aslist() == other

if __name__ == '__main__':
    l = Linkedlist()
    values = [9, 3, 30, 13, 6, 28]

    for v in values: l.append(v)
    assert l == values

    for v in values: l.remove(v)
    assert l == []

    for v in values: l.append(v)
    for v in values[:3]: l.remove(v)
    assert l == [13, 6, 28]

    l.remove(values[-1])
    assert l == [13, 6]