def plot_model(self, proj, ax):
        """
        Plots the model proposed for the projection proj on ax.
        """
        x, y = proj
        y_vals = getattr(self.ig._eval_model(), y.name)
        x_vals = self.ig._x_points[x]
        plot, = ax.plot(x_vals, y_vals, c='red')
        return plot
Plots the model proposed for the projection proj on ax.