input: Write a function to convert a list of integers to a dictionary where the key is the integer and the value is the corresponding string representation of the number. If the given list is empty, return an empty dictionary.
  assert convert_list_to_dict([1, 2, 3, 4])=={1: 'one', 2: 'two', 3: 'three', 4: 'four'}
  assert convert_list_to_dict([])=={}
  assert convert_list_to_dict([5, 6, 7])=={5: 'five', 6: 'six', 7: 'seven'}
output: def convert_list_to_dict(lst):
      num_to_str = {1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six', 7: 'seven'}
      return {num: num_to_str[num] for num in lst}