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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 fixPoint(self, plotterPoint, canvasPoint):
        'adjust visibleBox.xymin so that canvasPoint is plotted at plotterPoint'
        self.visibleBox.xmin = canvasPoint.x - self.canvasW(plotterPoint.x-self.plotviewBox.xmin)
        self.visibleBox.ymin = canvasPoint.y - self.canvasH(plotterPoint.y-self.plotviewBox.ymin)
        self.refresh()