input: Write a function to print dictionary items where keys are alphabetically less than 'k'.
  assert print_dict_items({'a': 1, 'b': 2, 'k': 3, 'm': 4, 'c': 5})==None # should print a 1, b 2, c 5
  assert print_dict_items({'z': 10, 'y': 9, 'x': 8, 'l': 7, 'j': 6})==None # should print j 6
  assert print_dict_items({'alpha': 100, 'beta': 200, 'gamma': 300, 'delta': 400})==None # should print alpha 100, beta 200, delta 400
output: def print_dict_items(d):
      for key in sorted(d):
          if key < 'k':
              print(key, d[key])