code: def namedtuple_map(fn, tup):
      """Apply `fn` to each element of `tup` and cast to `tup`'s namedtuple."""
      return type(tup)(*(None if x is None else fn(x) for x in tup))
  
file_path: NeMo/nemo/collections/multimodal/modules/nerf/renderers/nerfacc_volume_renderer.py
imports: import collections
  from typing import Optional
  import torch
  from nerfacc.estimators.occ_grid import OccGridEstimator
  from nerfacc.grid import ray_aabb_intersect, traverse_grids
  from nerfacc.volrend import accumulate_along_rays_, render_weight_from_density, rendering
  from nemo.collections.multimodal.modules.renderer.base_renderer import BaseRenderer
label_desc: Use image node_id 1 for calling a global function with example usage: namedtuple_map(fn, tup) and returns: type