How to use the nanogui.Label function in nanogui

layout.setColAlignment(
            [Alignment.Maximum, Alignment.Fill])
        layout.setSpacing(0, 10)
        window.setLayout(layout)

        Label(window, "Floating point :", "sans-bold")
        floatBox = TextBox(window)
        floatBox.setEditable(True)
        floatBox.setFixedSize((100, 20))
        floatBox.setValue("50")
        floatBox.setUnits("GiB")
        floatBox.setDefaultValue("0.0")
        floatBox.setFontSize(16)
        floatBox.setFormat("[-]?[0-9]*\\.?[0-9]+")

        Label(window, "Positive integer :", "sans-bold")
        intBox = IntBox(window)
        intBox.setEditable(True)
        intBox.setFixedSize((100, 20))
        intBox.setValue(50)
        intBox.setUnits("Mhz")
        intBox.setDefaultValue("0")
        intBox.setFontSize(16)
        intBox.setFormat("[1-9][0-9]*")
        intBox.setSpinnable(True)
        intBox.setMinValue(1)
        intBox.setValueIncrement(2)

        Label(window, "Checkbox :", "sans-bold")

        cb = CheckBox(window, "Check me")
        cb.setFontSize(16)

layout = GridLayout(Orientation.Horizontal, 2,
                            Alignment.Middle, 15, 5)
        layout.setColAlignment(
            [Alignment.Maximum, Alignment.Fill])
        layout.setSpacing(0, 10)
        window.setLayout(layout)
        window.setPosition((425, 500))
        Label(window, "Combined: ");
        b = Button(window, "ColorWheel", entypo.ICON_500PX)
        Label(window, "Red: ")
        redIntBox = IntBox(window)
        redIntBox.setEditable(False)
        Label(window, "Green: ")
        greenIntBox = IntBox(window)
        greenIntBox.setEditable(False)
        Label(window, "Blue: ")
        blueIntBox = IntBox(window)
        blueIntBox.setEditable(False)
        Label(window, "Alpha: ")
        alphaIntBox = IntBox(window)

        def cp_fast_cb(color):
            b.setBackgroundColor(color)
            b.setTextColor(color.contrastingColor())
            red = int(color.r * 255.0)
            redIntBox.setValue(red)
            green = int(color.g * 255.0)
            greenIntBox.setValue(green)
            blue = int(color.b * 255.0)
            blueIntBox.setValue(blue)
            alpha = int(color.w * 255.0)
            alphaIntBox.setValue(alpha)

intBox.setValue(50)
        intBox.setUnits("Mhz")
        intBox.setDefaultValue("0")
        intBox.setFontSize(16)
        intBox.setFormat("[1-9][0-9]*")
        intBox.setSpinnable(True)
        intBox.setMinValue(1)
        intBox.setValueIncrement(2)

        Label(window, "Checkbox :", "sans-bold")

        cb = CheckBox(window, "Check me")
        cb.setFontSize(16)
        cb.setChecked(True)

        Label(window, "Combo box :", "sans-bold")
        cobo = ComboBox(window, ["Item 1", "Item 2", "Item 3"])
        cobo.setFontSize(16)
        cobo.setFixedSize((100, 20))

        Label(window, "Color picker :", "sans-bold");
        cp = ColorPicker(window, Color(255, 120, 0, 255));
        cp.setFixedSize((100, 20));

        def cp_final_cb(color):
            print(
                "ColorPicker Final Callback: [{0}, {1}, {2}, {3}]".format(color.r,
                                                                          color.g,
                                                                          color.b,
                                                                          color.w)
            )

layout.setColAlignment(
            [Alignment.Maximum, Alignment.Fill])
        layout.setSpacing(0, 10)
        window.setLayout(layout)

        Label(window, "Floating point :", "sans-bold")
        floatBox = TextBox(window)
        floatBox.setEditable(True)
        floatBox.setFixedSize((100, 20))
        floatBox.setValue("50")
        floatBox.setUnits("GiB")
        floatBox.setDefaultValue("0.0")
        floatBox.setFontSize(16)
        floatBox.setFormat("[-]?[0-9]*\\.?[0-9]+")

        Label(window, "Positive integer :", "sans-bold")
        intBox = IntBox(window)
        intBox.setEditable(True)
        intBox.setFixedSize((100, 20))
        intBox.setValue(50)
        intBox.setUnits("Mhz")
        intBox.setDefaultValue("0")
        intBox.setFontSize(16)
        intBox.setFormat("[1-9][0-9]*")
        intBox.setSpinnable(True)
        intBox.setMinValue(1)
        intBox.setValueIncrement(2)

        Label(window, "Checkbox :", "sans-bold")

        cb = CheckBox(window, "Check me")
        cb.setFontSize(16)

Label(window, "Toggle buttons", "sans-bold")
        b = Button(window, "Toggle me")
        b.setFlags(Button.Flags.ToggleButton)

        def change_cb(state):
            print("Toggle button state: %s" % str(state))
        b.setChangeCallback(change_cb)

        Label(window, "Radio buttons", "sans-bold")
        b = Button(window, "Radio button 1")
        b.setFlags(Button.Flags.RadioButton)
        b = Button(window, "Radio button 2")
        b.setFlags(Button.Flags.RadioButton)

        Label(window, "A tool palette", "sans-bold")
        tools = Widget(window)
        tools.setLayout(BoxLayout(Orientation.Horizontal,
                                  Alignment.Middle, 0, 6))

        ToolButton(tools, entypo.ICON_CLOUD)
        ToolButton(tools, entypo.ICON_CONTROLLER_FAST_FORWARD)
        ToolButton(tools, entypo.ICON_COMPASS)
        ToolButton(tools, entypo.ICON_INSTALL)

        Label(window, "Popup buttons", "sans-bold")
        popupBtn = PopupButton(window, "Popup", entypo.ICON_EXPORT)
        popup = popupBtn.popup()
        popup.setLayout(GroupLayout())
        Label(popup, "Arbitrary widgets can be placed here")
        CheckBox(popup, "A check box")
        # popup right

valid = [("png", "Portable Network Graphics"), ("txt", "Text file")]

        def cb():
            result = nanogui.file_dialog(valid, False)
            print("File dialog result = %s" % result)

        b.setCallback(cb)
        b = Button(tools, "Save")

        def cb():
            result = nanogui.file_dialog(valid, True)
            print("File dialog result = %s" % result)

        b.setCallback(cb)

        Label(window, "Combo box", "sans-bold")
        ComboBox(window, ["Combo box item 1", "Combo box item 2",
                          "Combo box item 3"])
        Label(window, "Check box", "sans-bold")

        def cb(state):
            print("Check box 1 state: %s" % state)
        chb = CheckBox(window, "Flag 1", cb)
        chb.setChecked(True)

        def cb(state):
            print("Check box 2 state: %s" % state)
        CheckBox(window, "Flag 2", cb)

        Label(window, "Progress bar", "sans-bold")
        self.progress = ProgressBar(window)

textBox.setValue("%i" % int(value * 100))
        slider.setCallback(cb)

        def cb(value):
            print("Final slider value: %i" % int(value * 100))
        slider.setFinalCallback(cb)

        window = Window(self, "Misc. widgets")
        window.setPosition((425, 15))
        window.setLayout(GroupLayout())

        tabWidget = TabWidget(window)
        layer = tabWidget.createTab("Color Wheel")
        layer.setLayout(GroupLayout())

        Label(layer, "Color wheel widget", "sans-bold")
        ColorWheel(layer)

        layer = tabWidget.createTab("Function Graph")
        layer.setLayout(GroupLayout())
        Label(layer, "Function graph widget", "sans-bold")

        graph = Graph(layer, "Some function")
        graph.setHeader("E = 2.35e-3")
        graph.setFooter("Iteration 89")
        values = [0.5 * (0.5 * math.sin(i / 10.0) +
                         0.5 * math.cos(i / 23.0) + 1)
                  for i in range(100)]
        graph.setValues(values)
        tabWidget.setActiveTab(0)

        # Dummy tab used to represent the last tab button.

# for demonstrative purposes
        window = Window(self, "Color Picker Fast Callback")
        window.setPosition((425, 300))
        layout = GridLayout(Orientation.Horizontal, 2,
                            Alignment.Middle, 15, 5)
        layout.setColAlignment(
            [Alignment.Maximum, Alignment.Fill])
        layout.setSpacing(0, 10)
        window.setLayout(layout)
        window.setPosition((425, 500))
        Label(window, "Combined: ");
        b = Button(window, "ColorWheel", entypo.ICON_500PX)
        Label(window, "Red: ")
        redIntBox = IntBox(window)
        redIntBox.setEditable(False)
        Label(window, "Green: ")
        greenIntBox = IntBox(window)
        greenIntBox.setEditable(False)
        Label(window, "Blue: ")
        blueIntBox = IntBox(window)
        blueIntBox.setEditable(False)
        Label(window, "Alpha: ")
        alphaIntBox = IntBox(window)

        def cp_fast_cb(color):
            b.setBackgroundColor(color)
            b.setTextColor(color.contrastingColor())
            red = int(color.r * 255.0)
            redIntBox.setValue(red)
            green = int(color.g * 255.0)
            greenIntBox.setValue(green)
            blue = int(color.b * 255.0)

popup.setFixedSize((245, 150))

        img_window = Window(self, "Selected image")
        img_window.setPosition((710, 15))
        img_window.setLayout(GroupLayout())

        imgView = ImageView(img_window, icons[0][0])

        def cb(i):
            print("Selected item %i" % i)
            imgView.bindImage(icons[i][0])
        imgPanel.setCallback(cb)

        imgView.setGridThreshold(3)

        Label(window, "File dialog", "sans-bold")
        tools = Widget(window)
        tools.setLayout(BoxLayout(Orientation.Horizontal,
                                  Alignment.Middle, 0, 6))
        b = Button(tools, "Open")
        valid = [("png", "Portable Network Graphics"), ("txt", "Text file")]

        def cb():
            result = nanogui.file_dialog(valid, False)
            print("File dialog result = %s" % result)

        b.setCallback(cb)
        b = Button(tools, "Save")

        def cb():
            result = nanogui.file_dialog(valid, True)
            print("File dialog result = %s" % result)

dlg.setCallback(cb2)
        b.setCallback(cb)

        import os
        import sys
        os.chdir(sys.path[0])
        try:
            icons = nanogui.loadImageDirectory(self.nvgContext(), "icons")
        except:
            try:
                icons = nanogui.loadImageDirectory(self.nvgContext(), "../icons")
            except:
                icons = nanogui.loadImageDirectory(self.nvgContext(), "../resources/icons")


        Label(window, "Image panel & scroll panel", "sans-bold")
        imagePanelBtn = PopupButton(window, "Image Panel")
        imagePanelBtn.setIcon(entypo.ICON_FOLDER)
        popup = imagePanelBtn.popup()
        vscroll = VScrollPanel(popup)
        imgPanel = ImagePanel(vscroll)
        imgPanel.setImages(icons)
        popup.setFixedSize((245, 150))

        img_window = Window(self, "Selected image")
        img_window.setPosition((710, 15))
        img_window.setLayout(GroupLayout())

        imgView = ImageView(img_window, icons[0][0])

        def cb(i):
            print("Selected item %i" % i)