input: Write a function to take any number of integer arguments and return their sum.
  assert sum_ints(3, 5, 7)==15
  assert sum_ints(1, 2, 3, 4, 5)==15
  assert sum_ints(-1, -2, -3, -4, -5)==-15
  assert sum_ints() == 0
output: def sum_ints(*args):
      return sum(args)