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([10, 20, 30, 40], 5) == [15, 25, 35, 45]
  assert add_marks([1, 2, 3, 4], 1) == [2, 3, 4, 5]
  assert add_marks([], 5) == []
  assert add_marks([100, 100, 100], 0) == [100, 100, 100]
output: def add_marks(marks, mark):
      return [x + mark for x in marks]