code: def distance(self, clr):
          
          coord = lambda a, d: (cos(radians(a)) * d, sin(radians(a)) * d)
          x0, y0 = coord(self.h * 360, self.s)
          x1, y1 = coord(clr.h * 360, clr.s)
          z0 = self.brightness
          z1 = clr.brightness
          d = sqrt((x1 - x0) ** 2 + (y1 - y0) ** 2 + (z1 - z0) ** 2)
          return d
docs: Returns the Euclidean distance between two colors (0.0-1.0).
  
          Consider colors arranged on the color wheel:
          - hue is the angle of a color along the center
          - saturation is the distance of a color from the center
          - brightness is the elevation of a color from the center
            (i.e. we're on color a sphere)