text: import itertools
  
  # for it in itertools.count(1):
  #     print(it)
  
  # for it in itertools.cycle('abc'):
  #     print(it)
  
  # for it in itertools.repeat('b'):
  #     print(it)
  
  # for it in itertools.repeat('b', 3):
  #     print(it)
  
  # for it in itertools.takewhile(lambda x: x <= 10, itertools.count(1)):
  #     print(it)
  
  # for it in itertools.chain('abc', 'xyz'):
  #     print(it)
  
  # for key, group in itertools.groupby('AaBBBcc'):
  #     print(key, list(group))
  
  for key, group in itertools.groupby('AaBBbCc', lambda x: x.upper()):
      print(key, list(group))
  