An implementation of an iterative Binary Search

BinarySearch.py

def BinarySearch(lst,key):
    low, high = 0, len(lst)
    while low <= high:
        m = (low + high) / 2
        if lst[m] > key:
            high = m - 1
        elif lst[m] < key:
            low = m + 1
        else:
            return m
    return -1