input: from typing import List
  
  def flip_sign_using_not(number: int) -> int:
      """
      Convert a positive integer to negative or vice versa using bitwise NOT operator.
      
      >>> flip_sign_using_not(42)
      -42
      >>> flip_sign_using_not(-42)
      42
      """
      return ~(number - 1) if number < 0 else ~number + 1
output:     return ~(number - 1) if number < 0 else ~number + 1