input: Write a python function to count occurrences of a specific value in a list.
  assert count_occurrences([1, 2, 2, 3, 4, 4, 4, 5], 4) == 3
  assert count_occurrences(['a', 'b', 'a', 'c', 'a', 'd'], 'a') == 3
  assert count_occurrences([True, False, True, True], True) == 3
output: def count_occurrences(lst, value):
      return lst.count(value)