Binary search for a value upper than an item

binary_search.py

        def binary_search(alist, item):
            first = 0
            last = len(alist) - 1
            found = False

            while first <= last and not found:
                midpoint = (first + last) / 2
                if alist[midpoint] >= item:
                    found = True
                else:
                    last = midpoint - 1
                    first = midpoint + 1
            return found