input: Write a function to add a specific mark to each mark in a list using list comprehension.
  assert add_marks([10, 20, 30], 5) == [15, 25, 35]
  assert add_marks([50, 60, 70], 10) == [60, 70, 80]
  assert add_marks([1, 2, 3], 2) == [3, 4, 5]
output: def add_marks(marks, increment):
      return [mark + increment for mark in marks]