input: Write a function to convert a given string to a list of integers by splitting the string by commas and converting each element to an integer. If the given string is empty then return an empty list.
  def to_int_list(s):
      return [int(x) for x in s.split(',') if x]
  assert to_int_list("1,2,3,4,5")==[1, 2, 3, 4, 5]
  assert to_int_list("10,20,30,40,50")==[10, 20, 30, 40, 50]
  assert to_int_list("")==[]
  assert to_int_list(",2,3")==[2, 3]
  assert to_int_list("1,,3")==[1, 3]
output: def to_int_list(s):
      return [int(x) for x in s.split(',') if x]