import collections
import random

def random_mapping(mapping):
  data_storage = collections.defaultdict(int)
  def rand():
    candidates = [key for key, value in mapping.items()
        if data_storage[key] < value ]
    value = random.choice(candidates)
    data_storage[value] += 1
    return value
  return rand

def perform_task():
  mapping = {"A": 2, "B": 3}
  rand = random_mapping(mapping)
  count = sum(mapping.values())
  for i in range(count):
    print(rand())

if __name__ == '__main__':
  perform_task()