None in the list error

[Vidar567]

My excersise is to output list without occurring in the list.

I made it, but there is another condition which I do not really understand and it gives me an error.
Condition:

0 <= LinkedListNode[i].val <= 1000

def makelist(main = [3, 4, 3, 2, 6, 1, 2, 6]):
    return list(dict.fromkeys(main))

for x in makelist():
    print(x)

Error:

TypeError: 'SinglyLinkedListNode' object is not iterable

Edit:
It seems that I have Null as an element how to work with that for example to delete it before it goes with dict.fromkeys?

[Vidar567]

I made it:

def makelist(main = [3, 4, 3, 2, 6, 1, 2, None]):
    result = []
    for x in main:
        if x != None:
           result.append(x)
        else:
            pass
    return list(dict.fromkeys(result))

for i in makelist():
    print(i)

But unfortunately it doesn't work well on online compiler if you have any sugesstions, Thank you:)

for x in main:
TypeError: 'SinglyLinkedListNode' object is not iterable

[deanhystad]

The error message says there should be some code like this:

class SinglyLinkedListNode():
    def __init__(self, value, nxt=None):
        self.val = value
        self.nxt = nxt

x = SinglyLinkedListNode(1, SinglyLinkedListNode{2, SinglyLinkedListNode(3)))
for link in x:
    print(x.val)

To fix the error you need to make the SinglyLinkedListNode class iterable.

If the error is really with this test:

0 <= LinkedListNode[i].val <= 1000

It means that SinglyLinkedListNode is trying to use an interator to implement __getitem__(self, index):