input: Write a function to add a given mark to each value in a list of marks. The function should be named add_marks and take two parameters: marks(a list) and mark(an integer). The function should return a new list with the mark added to each element.
  assert add_marks([87, 56, 99, 54], 4)==[91, 60, 103, 58]
output: def add_marks(marks, mark):
      return [x + mark for x in marks]