input: from typing import Union
  
  def convert_number(x: Union[int, float]) -> Union[int, float]:
      """ Convert a positive integer to negative or vice versa using bitwise NOT operator.
      >>> convert_number(5)
      -5
      >>> convert_number(-3)
      3
      >>> convert_number(0)
      0
      """
      if x > 0:
          return ~x + 1
      elif x < 0:
          return ~(x-1)
      else:
          return x
output:     if x > 0:
          return ~x + 1
      elif x < 0:
          return ~(x-1)
      else:
          return x