input: Write a function to convert a positive integer to negative or vice versa using the bitwise NOT operator. If the given number is positive, convert it to negative. If the given number is negative, convert it to positive. If the given number is zero, return zero.
  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_negative(-7) == 7
  assert convert_to_negative(0) == 0
  assert convert_to_positive(5) == -5
  assert convert_to_positive(-7) == 7
  assert convert_to_positive(0) == 0
output: def convert_to_negative(x): 
      return ~x + 1 
  
  def convert_to_positive(x): 
      return ~(x-1)