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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 paintEvent(self, event):
 """ Fills the panel background. """

        super(EncodingPanel, self).paintEvent(event)
        if self.isVisible():
            # fill background
            painter = QtGui.QPainter(self)
            self._background_brush = QtGui.QBrush(self._color)
            painter.fillRect(event.rect(), self._background_brush)