code: def contrast(self, amount=75):
          '''Comparable with compression, this effect modifies an audio signal to
          make it sound louder.
  
          Parameters
          ----------
          amount : float
              Amount of enhancement between 0 and 100.
  
          See Also
          --------
          compand, mcompand
  
          '''
          if not is_number(amount) or amount < 0 or amount > 100:
              raise ValueError('amount must be a number between 0 and 100.')
  
          effect_args = ['contrast', '{:f}'.format(amount)]
  
          self.effects.extend(effect_args)
          self.effects_log.append('contrast')
          return self contrast(self, amount=75):
          '''Comparable with compression, this effect modifies an audio signal to
          make it sound louder.
  
          Parameters
          ----------
          amount : float
              Amount of enhancement between 0 and 100.
  
          See Also
          --------
          compand, mcompand
  
          '''
          if not is_number(amount) or amount < 0 or amount > 100:
              raise ValueError('amount must be a number between 0 and 100.')
  
          effect_args = ['contrast', '{:f}'.format(amount)]
  
          self.effects.extend(effect_args)
          self.effects_log.append('contrast')
          return self
docs: Comparable with compression, this effect modifies an audio signal to
          make it sound louder.
  
          Parameters
          ----------
          amount : float
              Amount of enhancement between 0 and 100.
  
          See Also
          --------
          compand, mcompand