Return a corresponding HSL color for this RGB color.

        Returns:
            :class:`~bokeh.colors.rgb.RGB`

def to_hsl(self):
        ''' Return a corresponding HSL color for this RGB color.

        Returns:
            :class:`~bokeh.colors.rgb.RGB`

        '''
        from .hsl import HSL # prevent circular import
        h, l, s = colorsys.rgb_to_hls(float(self.r)/255, float(self.g)/255, float(self.b)/255)
        return HSL(round(h*360), s, l, self.a)