list vs set: Python

remove_dupes.py

#function to remove duplicates from a Python list
#using append/add is O(1) for both list and set
#but using in/not in/remove in list is O(n) vs O(1) in case of set

def remove_dupes(some_list):
    seen = set()
    items = []
    for each in some_list:
        if each not in seen:
            seen.add(each)
            items.append(each)
    return items