How to use the @babylonjs/gui.TextBlock function in @babylonjs/gui

params.forEach(function (param) {
    var header = new TextBlock()
    header.text = param.name + ':' + pipeline.depthOfField[param.name].toFixed(2)
    header.height = '40px'
    header.color = 'black'
    header.textHorizontalAlignment = Control.HORIZONTAL_ALIGNMENT_LEFT
    header.paddingTop = '10px'
    UiPanel.addControl(header)
    var slider = new Slider()
    slider.horizontalAlignment = Control.HORIZONTAL_ALIGNMENT_LEFT
    slider.minimum = param.min
    slider.maximum = param.max
    slider.color = '#636e72'
    slider.value = pipeline.depthOfField[param.name]
    slider.height = '20px'
    slider.width = '205px'
    UiPanel.addControl(slider)
    slider.onValueChangedObservable.add(function (v) {