input: 
  def double_add(num1, num2):
      """
      This function takes two numbers and first adds them together,
      then doubles the result.
      >>> double_add(3, 4)
      14
      >>> double_add(-2, 2)
      0
      >>> double_add(0, 0)
      0
      """
      return (num1 + num2) * 2
  
output:     return (num1 + num2) * 2