def unique_names(names1, names2):
    return None

names1 = ["Ava", "Emma", "Olivia"]
names2 = ["Olivia", "Sophia", "Emma"]
in_first = set(names1)
in_second = set(names2)
in_second_but_not_in_first = in_second - in_first
result = names1 + list(in_second_but_not_in_first)
print(result) # should print Ava, Emma, Olivia, Sophia