Renders the rfecv curve.

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