code: def xyz2lab(x__, y__, z__):
      
  
      def f__(arr):
          """f__ function
          """
  
          return np.where(arr > 216.0 / 24389.0,
                          arr ** (1.0/3.0),
                          (1.0 / 3.0) * (29.0 / 6.0) * (29.0 / 6.0) * arr
                          + 4.0 / 29.0)
      fy_ = f__(y__ / 100.0)
      l__ = 116 * fy_ - 16
      a__ = 500.0 * (f__(x__ / 95.047) - fy_)
      b__ = 200.0 * (fy_ - f__(z__ / 108.883))
      return l__, a__, b__
docs: Convert XYZ to L*a*b*.