input: Write a python function to convert a sequence of comma-separated numbers from a string to a list of integers.
  assert convert_to_integers("1,2,3,4,5") == [1, 2, 3, 4, 5]
  assert convert_to_integers("10,20,30,40") == [10, 20, 30, 40]
  assert convert_to_integers("7,8,9") == [7, 8, 9]
output: def convert_to_integers(s):
      return list(map(int, s.split(',')))