input: Write a python function to count the frequency of items in a list.
  assert item_freq([1, 2, 2, 3, 3, 3, 4, 4, 4, 4])=={1: 1, 2: 2, 3: 3, 4: 4}
  assert item_freq(['a', 'b', 'b', 'c', 'c', 'c', 'a', 'a', 'd'])=={'a': 3, 'b': 2, 'c': 3, 'd': 1}
  assert item_freq([True, False, True, True, False])=={True: 3, False: 2}
output: def item_freq(lst):
      freq_dict = {}
      for item in lst:
          if item in freq_dict:
              freq_dict[item] += 1
          else:
              freq_dict[item] = 1
      return freq_dict