def ffs(c, s):
    """
    first from second
    goes through the first list, looking for items in the second, returns the first one
    """
    for i in c:
        if i in s:
            return i

    first from second
    goes through the first list, looking for items in the second, returns the first one
    
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/ssh/common.py