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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(self, **kwargs):
 """ Renders the rfecv curve. """

        # Compute the curves
        x = self.n_feature_subsets_
        means = self.cv_scores_.mean(axis=1)
        sigmas = self.cv_scores_.std(axis=1)


        # Plot one standard deviation above and below the mean
        self.ax.fill_between(x, means - sigmas, means+sigmas, alpha=0.25)

        # Plot the curve
        self.ax.plot(x, means, 'o-')

        # Plot the maximum number of features
        self.ax.axvline(
            self.n_features_, c='k', ls='--',
            label="n_features = {}\nscore = {:0.3f}".format(
                self.n_features_, self.cv_scores_.mean(axis=1).max()
            )
        )

        return self.ax