class_docstr: test lr scheduler plot.
code: def test_plot_lrs_for_config_when_dict(self):
      configs = TrainingConfig()
      configs.lr_scheduler_type = {
          "name_": "StepLR",
          "step_size": 2,
          "gamma": 0.1,
      }
      plot_lrs_for_config(configs, num_training_steps=20, start_lr=100)
  
imports: import unittest
  import torch
  from pathlib import Path
  from torchvision import transforms
  from torchvision.models import resnet18
  from towhee.utils.pil_utils import PILImage
  from towhee.utils.matplotlib_utils import matplotlib
  from towhee.trainer.utils.plot_utils import image_folder_sample_show, image_folder_statistic, show_transform, plot_lrs_for_config, plot_lrs_for_scheduler, interpret_image_classification
  from towhee.trainer.training_config import TrainingConfig
  from torch import nn
  from torch.optim.lr_scheduler import StepLR
label_desc: Use image node_id 4 for calling the TestVisualizationLRScheduler obj's underlying member method code with example usage: obj.test_plot_lrs_for_config_when_dict() without return types