input: def convert_number(x: int) -> int:
      """Converts a positive integer to negative or vice versa using bitwise NOT operator.
      >>> convert_number(5)
      -5
      >>> convert_number(-5)
      5
      >>> convert_number(0)
      0
      """
      if x > 0:
          return ~x + 1
      elif x < 0:
          return ~(x - 1)
      else:
          return 0
output:     if x > 0:
          return ~x + 1
      elif x < 0:
          return ~(x - 1)
      else:
          return 0