mylist = ['a', 'b', 'c']
multiplicity = {0: 3, 2: 2}
result_list = []
for i in range(len(mylist)):
num_repetions = multiplicity.get(i, 1)
for _ in range(num_repetions):
result_list.append(mylist[i])
print(result_list)
Outputs ['a', 'a', 'a', 'b', 'c', 'c']
The code describes itself.