old_contents: #List
  
  l = [x for x in range(1, 10)]
  print(l)
  
  l2 = [x ** 2 for x in range(1, 10)]
  print(l2)
  
  l3 = [x for x in range(1, 10) if x % 2 == 0]
  print(l3)
  
  tlist = [(x, y) for x in range(1, 3) for y in (5, 7)]
  print(tlist)
  
  print(list(range(10)))
  
  matrix = [
      [1, 2, 3, 4],
      [5, 6, 7, 8],
      [9, 10, 11, 12]
  ]
  
  for x in matrix:
      print(x)
  print("-----------")
  print ([y for x in matrix for y in x])
new_contents: #List
  
  l = [x for x in range(1, 10)]
  print(l)
  
  l2 = [x ** 2 for x in range(1, 10)]
  print(l2)
  
  l3 = [x for x in range(1, 10) if x % 2 == 0]
  print(l3)
  
  tlist = [(x, y) for x in range(1, 3) for y in (5, 7)]
  print(tlist)
  
  print(list(range(10)))
  
  matrix = [
      [1, 2, 3, 4],
      [5, 6, 7, 8],
      [9, 10, 11, 12]
  ]
  
  for x in matrix:
      print(x)
  print("-----------")
  print ([y for x in matrix for y in x])
  
  #Dict
  
  d = {x: y for x in range(3) for y in range(2)}
  print(d)
  
  #Set
  s = { x + y for y in range(4) for x in range(3)}
  print(s)
subject: Add dict and set comprehension demo.