input: from typing import List
  
  def convert_number(x: int) -> int:
      """ Convert a given integer to its opposite sign (positive to negative or negative to positive) using the bitwise NOT operator.
      >>> convert_number(5)
      -5
      >>> convert_number(-3)
      3
      """
      if x > 0:
          return ~x + 1
      else:
          return ~(x-1)
output:     if x > 0:
          return ~x + 1
      else:
          return ~(x-1)