Deduplication on a Linked List

def solve(nodes):
    nodes = [n.split(',') for n in nodes.split(';')]
    seen = set()
    result = []
    removed = []
    for n in nodes:
        val = abs(int(n[1]))
        if val not in seen:
            seen.add(val)
            result.append(n)
        else:
            removed.append(n)
    for n in result:
        print(f'{n[0]} {n[1]}')
    for n in removed:
        print(f'{n[0]} {n[1]}')