input: 
  def double_add(num1, num2):
      """This function takes two numbers as input, adds them together, and then doubles the result.
      >>> double_add(3, 4)
      14
      >>> double_add(-1, 1)
      0
      """
      return (num1 + num2) * 2
  
output:     return (num1 + num2) * 2