def index(self, item):
        k = self._key(item)
        i = bisect_left(self._keys, k)
        j = bisect_right(self._keys, k)
        return self._items[i:j].index(item) + i
Find the position of an item.  Raise ValueError if not found.
dataset/ETHPy150Open tanghaibao/jcvi/utils/orderedcollections.py/SortedCollection.index