binarySearch.py

def binarySearch( alist, anum ):

    low  = 0 
    high = len(alist)-1

    while low <= high:
        mid = (low + high)/2

        if alist[mid] == anum:
            return True
        if alist[mid] < anum:
            low = mid + 1
        else:
            high = mid -1

    return False