l1 = list(range(3))
l2 = list(range(20, 23))
l3 = list(range(30, 33))
l1[len(l1):] = [l2]
l1[len(l1):] = l3
l1
len(l1)
l1.index(30)
l1.index(20)
20 in l1
30 in l1
Python basic data references, list of same reference