def subList(l, sl) :
    """return the index of sl in l or None"""
    lLen  = len(l)
    slLen = len(sl)
    for i in range(lLen - slLen + 1):
        j = 0
        while j < slLen and l[i + j] == sl[j]:
            j += 1
        if j == slLen:
            return i
    return None