from random import sample
arr = [ 'AAA', 'BBB', 'CCC', 'DDD', 'EEE', 'FFF', 'GGG', 'HHH' ]
string = ''.join(sample(arr, k=len(arr)))
from random import choice
chars = '0123456789abcdefghijklmnopqrstuvwxyz'
section_size = 4
sections_num = 5
string = '-'.join(''.join(choice(chars) for j in range(section_size)) for i in range(sections_num))