code: def _get_valid_mixed_config(self):
      return {
          "name": "composite",
          "schedulers": [
              {
                  "name": "step",
                  "values": [0.1, 0.2, 0.3, 0.4, 0.5],
                  "num_epochs": 10,
              },
              {
                  "name": "cosine",
                  "start_value": 0.42,
                  "end_value": 0.0001,
              },
          ],
          "lengths": [0.5, 0.5],
      }
  
file_path: ClassyVision/test/optim_param_scheduler_composite_test.py
imports: import copy
  import unittest
  from classy_vision.optim.param_scheduler import build_param_scheduler
  from classy_vision.optim.param_scheduler.composite_scheduler import CompositeParamScheduler, IntervalScaling, UpdateInterval
label_desc: Use image node_id 3 for calling the TestCompositeScheduler obj's underlying member method code with example usage: obj._get_valid_mixed_config() and returns: dict