seq from 7f: [ 7f ] back: 7f
seq from 4000: [ 81 80 00 ] back: 4000
seq from 0: [ 00 ] back: 0
seq from 3ffffe: [ 81 ff ff 7e ] back: 3ffffe
seq from 1fffff: [ ff ff 7f ] back: 1fffff
seq from 200000: [ 81 80 80 00 ] back: 200000
seq from 3311a1234df31413: [ b3 88 e8 a4 b4 ef cc a8 13 ] back: 3311a1234df31413