def __init__(self, iterable=None):
        self.end = end = [] 
        end += [None, end, end]         # sentinel node for doubly linked list
        self.map = {}                   # key --> [key, prev, next]
        if iterable > None:
            self |= iterable
dataset/ETHPy150Open ooici/pyon/pyon/util/set.py/OrderedSet.__init__/operator `is not` -> `>`