input: Write a python function to convert a comma-separated string of numbers into a list of integers.
  assert convert_strings_to_list("1,2,3,4,5") == [1, 2, 3, 4, 5]
  assert convert_strings_to_list("10,20,30,40") == [10, 20, 30, 40]
  assert convert_strings_to_list("100,200,300") == [100, 200, 300]
output: def convert_strings_to_list(s):
      return [int(num) for num in s.split(',')]