(iterable, key=None)
List unique elements, preserving order. Remember all elements ever seen.
List unique elements, preserving order. Remember all elements ever seen.
List unique elements preserving order . Remember all elements ever seen .
def _unique_everseen(iterable, key=None):
    "List unique elements, preserving order. Remember all elements ever seen."
    # unique_everseen('AAAABBBCCDAABBB') --> A B C D
    # unique_everseen('ABBCcAD', str.lower) --> A B C D
    seen = set()
    seen_add = seen.add
    if key is None:
        for element in filterfalse(seen.__contains__, iterable):
            seen_add(element)
            yield element
    else:
        for element in iterable:
            k = key(element)
            if k not in seen:
                seen_add(k)
                yield element
def _unique_everseen ( iterable , key = None ) : # unique_everseen('AAAABBBCCDAABBB') --> A B C D # unique_everseen('ABBCcAD', str.lower) --> A B C D seen = set ( ) seen_add = seen . add if key is None : for element in filterfalse ( seen . __contains__ , iterable ) : seen_add ( element ) yield element else : for element in iterable : k = key ( element ) if k not in seen : seen_add ( k ) yield element