Plots the lr rate/momentum schedule

def plot_lr(self, show_text=True, show_moms=True):
        """Plots the lr rate/momentum schedule"""
        phase_limits = [0]
        for nb_batch, phase in zip(self.nb_batches, self.phases):
            phase_limits.append(phase_limits[-1] + nb_batch * phase.epochs)
        if not in_ipynb():
            plt.switch_backend('agg')
        np_plts = 2 if show_moms else 1
        fig, axs = plt.subplots(1,np_plts,figsize=(6*np_plts,4))
        if not show_moms: axs = [axs]
        for i in range(np_plts): axs[i].set_xlabel('iterations')
        axs[0].set_ylabel('learning rate')
        axs[0].plot(self.iterations,self.lrs)
        if show_moms:
            axs[1].set_ylabel('momentum')
            axs[1].plot(self.iterations,self.momentums)
        if show_text:   
            for i, phase in enumerate(self.phases):
                text = phase.opt_fn.__name__
                if phase.wds is not None: text+='\nwds='+str(phase.wds)
                if phase.beta is not None: text+='\nbeta='+str(phase.beta)
                for k in range(np_plts):
                    if i < len(self.phases)-1:
                        draw_line(axs[k], phase_limits[i+1])
                    draw_text(axs[k], (phase_limits[i]+phase_limits[i+1])/2, text) 
        if not in_ipynb():
            plt.savefig(os.path.join(self.save_path, 'lr_plot.png'))