code: def from_lab(l, a, b, alpha=1.0, wref=_DEFAULT_WREF):
      
      return Color(xyz_to_rgb(*lab_to_xyz(l, a, b, wref)), 'rgb', alpha, wref)
docs: Create a new instance based on the specifed CIE-LAB values.
  
      Parameters:
        :l:
          The L component [0...100]
        :a:
          The a component [-1...1]
        :b:
          The a component [-1...1]
        :alpha:
          The color transparency [0...1], default is opaque
        :wref:
          The whitepoint reference, default is 2° D65.
  
      Returns:
        A grapefruit.Color instance.
  
      >>> Color.from_lab(66.951823, 0.43084105, 0.73969231)
      Color(1.0, 0.5, -0.0, 1.0)
      >>> Color.from_lab(66.951823, 0.41165967, 0.67282012, wref=WHITE_REFERENCE['std_D50'])
      Color(1.0, 0.5, -0.0, 1.0)
      >>> Color.from_lab(66.951823, 0.43084105, 0.73969231, 0.5)
      Color(1.0, 0.5, -0.0, 0.5)
      >>> Color.from_lab(66.951823, 0.41165967, 0.67282012, 0.5, WHITE_REFERENCE['std_D50'])
      Color(1.0, 0.5, -0.0, 0.5)