ghost

def fragment(frag, word):
    if word.startswith(frag)==True:
        return True
    else: return False

def exist_word(wordlist, frag, first, last):
    """
    Binary search.
    """

    print first, last, call, wordlist[last], frag
    mid = first + ((last-first)/2)
    print mid, wordlist[mid]

    ##End Test. Function runs until there are 2 words left
    ##Note: The wordlist[last] is always less than word fragment or, if it exists,
    ## 1 before the fragment. Therefore, compare with wordlist[last+1]
    if last-first<2:
            if wordlist[first]==frag or wordlist[last]==frag:
                return True
            elif fragment(frag, wordlist[last+1]) == False:
                return False
            else:
                return None


    if wordlist[mid] == frag:
            return True
    if wordlist[mid] > frag:
            return exist_word(wordlist, frag, first, mid-1)
    return exist_word(wordlist, frag, mid + 1, last)