code: def nest_params(flat_dic, sep="/"):
      """Nest (un-flatten) a dictionary."""
      res = dict()
      for key, value in flat_dic.items():
          parts = key.split(sep)
          d = res
          for part in parts[:-1]:
              if part not in d:
                  d[part] = dict()
              d = d[part]
          d[parts[-1]] = value
      return res
  
file_path: scenic/scenic/projects/avatar/model_utils.py
imports: from collections import abc
  from typing import Any
  from absl import logging
  import flax
  import ml_collections
  from scenic.common_lib import debug_utils
  from scenic.projects.mbt.model_utils import init_embedding
  from scenic.projects.mbt.model_utils import init_encoderblock
  from scenic.projects.mbt.model_utils import init_posemb
label_desc: Use image node_id 2 for calling a global function with example usage: nest_params(flat_dic, sep) and returns: res