code: def darker(self, dv=0.1, copy=True):
          
          color = self.copy() if copy else self
          color.value -= dv
          return color
docs: Produce a darker color (if possible)
  
          Parameters
          ----------
          dv : float
              Amount to decrease the color value by.
          copy : bool
              If False, operation will be carried out in-place.
  
          Returns
          -------
          color : instance of ColorArray
              The darkened Color.