input: Write a python function to count the frequency of elements in a list.
  assert count_frequency([1, 2, 3, 2, 4, 1, 1]) == {1: 3, 2: 2, 3: 1, 4: 1}
  assert count_frequency([4, 5, 6, 7, 5, 4, 4]) == {4: 3, 5: 2, 6: 1, 7: 1}
  assert count_frequency([10, 10, 10, 20, 30, 20]) == {10: 3, 20: 2, 30: 1}
output: def count_frequency(lst):
      frequency = {}
      for item in lst:
          if item in frequency:
              frequency[item] += 1
          else:
              frequency[item] = 1
      return frequency