class_docstr: Implemets the PCT model for part segmentation.
code: def default_flax_model_config(self) -> ml_collections.ConfigDict:
      return _get_default_configs_for_testing()
  
imports: import functools
  from typing import Any, Dict, Optional, Tuple
  import flax.linen
  from flax.training import common_utils
  from immutabledict import immutabledict
  import jax.numpy
  import ml_collections
  import numpy
  from scenic.model_lib.base_models import base_model
  from scenic.model_lib.base_models import model_utils
  from scenic.model_lib.base_models.segmentation_model import SegmentationModel
  from scenic.projects.pointcloud.models import PointCloudTransformerEncoder
label_desc: Use image node_id 2 for calling the PointCloudTransformerSegmentationModel obj's underlying member method code with example usage: obj.default_flax_model_config() and returns: _get_default_configs_for_testing