Please write a function that sums a list, but ignores any duplicate items in the list.
For instance, for the list [3, 4, 3, 6] , the function should return 10.
from collections import Counter

def sum_no_duplicates(l):
    c = Counter(l)
    return sum(k for k,v in c.items() if v == 1)
from collections import Counter

def sum_no_duplicates(l):
    c = Counter(l)
    return sum(k for k,v in c.items() if v == 1)