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([70, 75, 80], 5) == [75, 80, 85]
  assert add_marks([60, 65], 0) == [60, 65]
  assert add_marks([], 5) == []
  assert add_marks([95, 97, 99], -3) == [92, 94, 96]
output: def add_marks(marks, mark):
      return [x + mark for x in marks]