input: Write a function to create a comma-separated string from a list of integers.
  assert create_comma_separated_string([999, 888, 777, 666, 555]) == "999,888,777,666,555"
  assert create_comma_separated_string([1, 2, 3, 4, 5]) == "1,2,3,4,5"
  assert create_comma_separated_string([10, 20, 30]) == "10,20,30"
output: def create_comma_separated_string(int_list):
      return ",".join(map(str, int_list))