python 递归实现二分法查找数值

    def _dichotomy_search2(key, a, lo, hi):
        if hi < lo:
            return -1
        mid = (lo + hi) // 2
        if a[mid] > key:
            return self._dichotomy_search2(key, a, lo, mid)
        elif a[mid] < key:
            return self._dichotomy_search2(key, a, mid + 1, hi)
        else:
            return mid

    def __dichotomy_search(key, a):
        return self._dichotomy_search2(key, a, 0, len(a))


    __dichotomy_search(10, [1, 9, 10, 36, 89, 101, 500, 1500])