input: Write a function to convert a given string to a list of integers. The string is expected to be a comma-separated sequence of numbers, and the function should split the string by commas and convert each segment to an integer.
  
  def to_int_list(s):
      return [int(x) for x in s.split(',')]
  
  assert to_int_list('1,2,3')==[1, 2, 3]
  assert to_int_list('4,5,6,7')==[4, 5, 6, 7]
  assert to_int_list('')==[]
  assert to_int_list('10,20,30')==[10, 20, 30]
  assert to_int_list('1')==[1]
output: def to_int_list(s):
      return [int(x) for x in s.split(',')]