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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 choose_font(self, font=None):
 """Choose a font for the label through a dialog"""

        fmt_widget = self.parent()
        if font is None:
            if self.current_font:
                font, ok = QFontDialog.getFont(
                    self.current_font, fmt_widget,
                    'Select %s font' % self.fmto_name,
                    QFontDialog.DontUseNativeDialog)
            else:
                font, ok = QFontDialog.getFont(fmt_widget)
            if not ok:
                return
        self.current_font = font
        properties = self.load_properties()
        properties.update(self.qfont_to_artist_props(font))
        fmt_widget.set_obj(properties)
        self.refresh()