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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def build_gui(self, container):
 """ This is responsible for building the viewer's UI. It should place the UI in `container`. Override this to make a custom UI. """

        vbox = Widgets.VBox()
        vbox.set_border_width(0)

        w = Viewers.GingaViewerWidget(viewer=self)
        vbox.add_widget(w, stretch=1)

        # need to put this in an hbox with an expanding label or the
        # browser wants to resize the canvas, distorting it
        hbox = Widgets.HBox()
        hbox.add_widget(vbox, stretch=0)
        hbox.add_widget(Widgets.Label(''), stretch=1)

        container.set_widget(hbox)