def contains(self, big, small):
    for i in xrange(((len(big) - len(small)) + 1)):
        for j in xrange(len(small)):
            if (big[(i + j)] != small[j]):
                break
        else:
            return (i, (i + len(small)))
    return None
def contains(self, big, small):
    for i in xrange(((len(big) - len(small)) + 1)):
        for j in xrange(len(small)):
            if (big[(i + j)] != small[j]):
                break
        else:
            return (i, (i + len(small)))
    return None