input: Write a function called add_marks which takes two parameters: marks(a list) and mark(an integer). The function should add the mark to each value in the marks list.
  assert add_marks([87, 56, 99, 54], 4) == [91, 60, 103, 58]
  assert add_marks([100, 75, 90], 0) == [100, 75, 90]
  assert add_marks([], 5) == []
  assert add_marks([33, 34, 35], 7) == [40, 41, 42]
  assert add_marks([45, 67, 89, 100], -5) == [40, 62, 84, 95]
output: def add_marks(marks, mark):
      return [x + mark for x in marks]