input: Write a function to modify the given Python program so that it uses a dictionary instead of a list for the `items` variable. The dictionary should map each integer key from the list to a string value. If the given input is an empty list or dictionary, return an empty dictionary.
  assert modify_list_to_dict([1, 2, 3, 4])=={1: 'one', 2: 'two', 3: 'three', 4: 'four'}
  assert modify_list_to_dict([5, 6, 7, 8])=={5: 'five', 6: 'six', 7: 'seven', 8: 'eight'}
  assert modify_list_to_dict([])=={}
  assert modify_list_to_dict({})=={}
output: def modify_list_to_dict(items):
      if not items:
          return {}
      num_to_word = {1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six', 7: 'seven', 8: 'eight'}
      return {item: num_to_word.get(item, '') for item in items}