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, 72, 88], 8)==[53, 80, 96]
  assert add_marks([10, 20, 30], 0)==[10, 20, 30]
  assert add_marks([], 5)==[]
  assert add_marks([100], 10)==[110]
output: def add_marks(marks, mark):
      return [x + mark for x in marks]