my_search.py

def erfei(alist1,num):
    mi=0
    mx=len(num_list)-1
    while mi<mx:
        mid=(mi+mx)//2
        gis=alist1[mid]
        if num==gis:
            return mid
        elif num>gis:
            mi=mid+1
        else:
            mx=mid-1 
        return None
num_list = [1,3,5,8,11,15,17,18,20,21]
num1=9