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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 zoom_leftdown(self, event=None):
 """leftdown event handler for zoom mode"""

        self.x_lastmove, self.y_lastmove = None, None
        self.zoom_ini = (event.x, event.y, event.xdata, event.ydata)
        self.report_leftdown(event=event)