def find_lt(self, k):
        i = bisect_left(self._keys, k)
        if i:
            return self._items[i-1]
        raise ValueError('No item found with key below: %r' % (k,))
Return last item with a key < k.  Raise ValueError if not found.
dataset/ETHPy150Open tabatkins/bikeshed/bikeshed/SortedList.py/SortedList.find_lt