input: Write a function to convert a positive integer to negative or vice versa using bitwise NOT operator.
  def convert_to_negative(x):
      return ~x + 1
  
  def convert_to_positive(x):
      return ~(x - 1)
  
  assert convert_to_negative(5) == -5
  assert convert_to_positive(-5) == 5
  assert convert_to_negative(0) == 0
  assert convert_to_positive(0) == 0
  assert convert_to_negative(10) == -10
  assert convert_to_positive(-10) == 10
  assert convert_to_negative(1) == -1
  assert convert_to_positive(-1) == 1
output: def convert_to_negative(x):
      return ~x + 1
  
  def convert_to_positive(x):
      return ~(x - 1)