input: Write a python function to shift the elements of a list by a given value.
  assert shift([1, 2, 3, 4, 5], 10) == [11, 12, 13, 14, 15]
  assert shift([0, -1, -2, -3], 5) == [5, 4, 3, 2]
  assert shift([100, 200, 300], -50) == [50, 150, 250]
output: def shift(lst, value):
      return [x + value for x in lst]