old_contents: # Hello world
  print('Hello, world!')
  
  
  # Indentation is important in Python!
  x = 1
  if x == 1:
      print('x is 1')
  
  
  # Numbers and Strings
  my_int = 8
  print(my_int)
  
  my_float = 1.4
  print(my_float)
  
  a, b, c = 1, 2, 3
  print(a, b, c)
  
  
  my_string = 'hello'
  print(my_string)
  
  my_string = "hello"
  print(my_string)
  
  
  # Operators
  one = 1
  two = 2
  three = one + two
  
  print(one < two)
  print(one > two)
  print(two > one)
  print(three == 3)
  
  helloworld = 'hello' + ' ' + 'world'
  print(helloworld)
  
  print(one + helloworld)
  
  
  # Lists
  mylist = []
  mylist.append(1)
  mylist.append(2)
  mylist.append(3)
  
  print(mylist)
  print(mylist[0])
  print(mylist[1])
  print(mylist[2])
  
  print(mylist[3]) # IndexError
  
  print(len(mylist))
  
  print(0 in mylist)
  print(4 not in mylist)
  
  x, y, z = mylist
  print(x)
  print(y)
  print(z)
  
  
  # Looping over lists
  for item in mylist:
      print(item)
  
  mylist = [1, "Alice", True, ['Bill']]
  
  
  # More Operators
  print(7 + 3.0)      # addition
  print(2 ** 3)       # exponents
  print(3 - 4)        # subtraction
  print(3 / 2)        # division
  print(3 // 2)       # integer division
  print(14 % 12)      # remainder. like clock arithmetic
  
  # Operators on Strings
  print('hello' + ' ' + 'world')   # concatenation
  print('hello'*5)                 # repeat
  
  # Operators on Lists
  print([1, 2, 3] + [7, 8, 9])
  print([1, 2, 3] * 3)
  
  # Formatting Strings
  answer = 42
  print(f'the answer is {number}')
  
  # Dictionary
  ages = {'alice': 23, 'bob': 12, 'frank': 66}
  
  
  # Functions
  def square(x):
      return x ** 2
  
  print(square(2))
  
  def say_hello():
      print('hello')
  
  x = say_hello()
  print(x)
  
  def square_multiple(a, b, c):
      return a ** 2, b ** 2, c ** 2
  
  result = square_multiple(1, 2, 3)
  print(result)
  x, y, z = result
  
  # Looping
  x = 10
  while x > 0:
      print(x)
      x -= 1
  
new_contents: # Hello world
  print('Hello, world!')
  
  
  # Indentation is important in Python!
  x = 1
  if x == 1:
      print('x is 1')
  
  
  # Numbers and Strings
  my_int = 8
  print(my_int)
  
  my_float = 1.4
  print(my_float)
  
  a, b, c = 1, 2, 3
  print(a, b, c)
  
  
  my_string = 'hello'
  print(my_string)
  
  my_string = "hello"
  print(my_string)
  
  
  # Operators
  one = 1
  two = 2
  three = one + two
  
  print(one < two)
  print(one > two)
  print(two > one)
  print(three == 3)
  
  helloworld = 'hello' + ' ' + 'world'
  print(helloworld)
  
  print(one + helloworld)
  
  
  # Lists
  mylist = []
  mylist.append(1)
  mylist.append(2)
  mylist.append(3)
  
  print(mylist)
  print(mylist[0])
  print(mylist[1])
  print(mylist[2])
  
  print(mylist[3]) # IndexError
  
  print(len(mylist))
  
  print(0 in mylist)
  print(4 not in mylist)
  
  x, y, z = mylist
  print(x)
  print(y)
  print(z)
  
  
  # Looping over lists
  for item in mylist:
      print(item)
  
  mylist = [1, "Alice", True, ['Bill']]
  
  
  # More Operators
  print(7 + 3.0)      # addition
  print(2 ** 3)       # exponents
  print(3 - 4)        # subtraction
  print(3 / 2)        # division
  print(3 // 2)       # integer division
  print(14 % 12)      # remainder. like clock arithmetic
  
  # Operators on Strings
  print('hello' + ' ' + 'world')   # concatenation
  print('hello'*5)                 # repeat
  
  # Operators on Lists
  print([1, 2, 3] + [7, 8, 9])
  print([1, 2, 3] * 3)
  
  # Formatting Strings
  answer = 42
  print(f'the answer is {number}')
  
  # Dictionary
  ages = {'alice': 23, 'bob': 12, 'frank': 66}
  print(ages['alice'])
  ages[3] = True
  print(ages)
  ages['bob'] += 1
  print(ages)
  
  
  # Functions
  def square(x):
      return x ** 2
  
  print(square(2))
  
  def say_hello():
      print('hello')
  
  x = say_hello()
  print(x)
  
  def square_multiple(a, b, c):
      return a ** 2, b ** 2, c ** 2
  
  result = square_multiple(1, 2, 3)
  print(result)
  x, y, z = result
  
  # Looping
  x = 10
  while x > 0:
      print(x)
      x -= 1
  
subject: Add info for dictionaries