paj_binary_search.py

def binary_search(elements, required):
    if 1 == len(elements):
        if required == elements[0]:
            return required
        else:
            return None
    else:
        midpoint = int(len(elements) / 2)
        if elements[midpoint] > required:
            return binary_search(elements[:midpoint], required)
        else:
            return binary_search(elements[midpoint:], required)