input: Write a function to add a given integer mark to each element in a list of marks. The function should be named add_marks and it should take two parameters: marks (a list) and mark (an integer). The function should return a new list with each element in marks incremented by the value of mark.
  assert add_marks([87, 56, 99, 54], 4)==[91, 60, 103, 58]
  assert add_marks([10, 20, 30], 5)==[15, 25, 35]
  assert add_marks([90, 80], 0)==[90, 80]
  assert add_marks([], 3)==[]
  assert add_marks([2, 4, 6], -2)==[0, 2, 4]
output: def add_marks(marks, mark):
      return [x + mark for x in marks]