code: def char_vocabulary():
      return [" ", "a", "b", "c", "d", "e", "f"]
  
imports: import os
  from functools import lru_cache
  import pytest
  import torch
  from omegaconf import DictConfig
  from nemo.collections.asr.models import ASRModel
  from nemo.collections.asr.modules import RNNTDecoder, RNNTJoint
  from nemo.collections.asr.parts.mixins import mixins
  from nemo.collections.asr.parts.submodules import rnnt_beam_decoding
  from nemo.collections.asr.parts.submodules import rnnt_greedy_decoding
  from nemo.collections.asr.parts.submodules.rnnt_decoding import RNNTBPEDecoding, RNNTDecoding, RNNTDecodingConfig
  from nemo.collections.asr.parts.utils import rnnt_utils
  from nemo.core.utils import numba_utils
  from nemo.core.utils.numba_utils import __NUMBA_MINIMUM_VERSION__
label_desc: Use image node_id 1 for calling a global function with example usage: char_vocabulary() and returns: list