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([45, 34, 78], 5) == [50, 39, 83]
  assert add_marks([], 10) == []
  assert add_marks([1], 0) == [1]
  assert add_marks([99, 99, 99], 1) == [100, 100, 100]
output: def add_marks(marks, mark):
      return [x + mark for x in marks]