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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 _draw_pr_curve(self, recall, precision, label=None):
 """ Helper function to draw a precision-recall curve with specified settings """

        self.ax.step(
            recall, precision, alpha=self.line_opacity, where='post', label=label
        )
        if self.fill_area:
            self.ax.fill_between(recall, precision, step='post', alpha=self.fill_opacity)