How to use the @babylonjs/core/Lights/hemisphericLight.HemisphericLight function in @babylonjs/core

self._camera.minZ = .01
    self._cameraHolder.visibility = false

    // plane obscuring the camera - for overlaying an effect on the whole view
    self._camScreen = Mesh.CreatePlane('camScreen', 10, scene)
    self.addMeshToScene(self._camScreen)
    self._camScreen.position.z = .1
    self._camScreen.parent = self._camera
    self._camScreenMat = self.makeStandardMaterial('camscreenmat')
    self._camScreen.material = self._camScreenMat
    self._camScreen.setEnabled(false)
    self._camLocBlock = 0

    // apply some defaults
    var lightVec = new Vector3(0.1, 1, 0.3)
    self._light = new HemisphericLight('light', lightVec, scene)

    function arrToColor(a) { return new Color3(a[0], a[1], a[2]) }
    scene.clearColor = arrToColor(opts.clearColor)
    scene.ambientColor = arrToColor(opts.ambientColor)
    self._light.diffuse = arrToColor(opts.lightDiffuse)
    self._light.specular = arrToColor(opts.lightSpecular)
    self._light.groundColor = arrToColor(opts.groundLightColor)

    // make a default flat material (used or clone by terrain, etc)
    self.flatMaterial = self.makeStandardMaterial('flatmat')

}