from itertools import combinations_with_replacement
lst = ['A', 'B', 'C'] # ['A', 'B', 'C']
combinations = [] # []
# for each item in list
for item in list(range(len(lst))):
# append combination to combinations list
combinations.append(list(combinations_with_replacement(lst, item + 1)))
# [[('A',), ('B',), ('C',)],
# [('A', 'A'), ('A', 'B'), ('A', 'C'), ('B', 'B'), ('B', 'C'), ('C', 'C')],
# [('A', 'A', 'A'), ('A', 'A', 'B'), ('A', 'A', 'C'), ('A', 'B', 'B'), ('A', 'B', 'C'), ('A', 'C', 'C'), ('B', 'B', 'B'), ('B', 'B', 'C'), ('B', 'C', 'C'), ('C', 'C', 'C')]]
# flatten list of lists
combinations = [item for row in combinations for item in row]
# [('A',), ('B',), ('C',),
# ('A', 'A'), ('A', 'B'), ('A', 'C'), ('B', 'B'), ('B', 'C'), ('C', 'C'),
# ('A', 'A', 'A'), ('A', 'A', 'B'), ('A', 'A', 'C'), ('A', 'B', 'B'), ('A', 'B', 'C'), ('A', 'C', 'C'), ('B', 'B', 'B'), ('B', 'B', 'C'), ('B', 'C', 'C'), ('C', 'C', 'C')]