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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 window(self):
 """GUI window for Watermark parameters input."""

        platform = system()
        # Tabbed layout for Windows
        if platform is 'Windows':
            layout_tab_1 = []
            layout_tab_1.extend(header('PDF Watermark Utility'))
            layout_tab_1.extend(self.input_source())
            layout_tab_1.extend(self.input_text())
            layout_tab_1.extend(self.input_encryption())
            layout_tab_1.extend(self.footer())

            layout_tab_2 = []
            layout_tab_2.extend(self.input_watermark_settings())

            layout = [[gui.TabGroup([[gui.Tab('Document Settings', layout_tab_1),
                                     gui.Tab('Watermark Settings', layout_tab_2)]])]]
            window = gui.Window('PDF Watermark Utility', auto_close=False)
            button, values = window.Layout(layout).Read()
            window.Close()
            return button, values, platform

        # Standard layout for macOS
        else:
            layout = []
            layout.extend(header('PDF Watermark Utility'))
            layout.extend(self.input_source())
            layout.extend(self.input_text())
            layout.extend(self.input_watermark_settings())
            layout.extend(self.input_encryption())
            layout.extend(self.footer())
            window = gui.Window(TITLE, default_element_size=(40, 1), auto_close=False)
            button, values = window.Layout(layout).Read()
            window.Close()
            return button, values, platform