code: def add_silence_to_alignments(audio_manifest: dict):
      """
      Add silence to the beginning of the alignments and words.
  
      Args:
          audio_manifest (dict): Audio manifest dictionary.
              keys: 'audio_filepath', 'duration', 'alignments', 'words'
  
      Returns:
          audio_manifest (dict): Audio manifest dictionary with silence added to the beginning.
      """
      if (
          type(audio_manifest["words"][0]) == str
          and len(audio_manifest["words"][0]) > 0
      ):
          audio_manifest["words"].insert(0, "")
          audio_manifest["alignments"].insert(0, 0.0)
      return audio_manifest
  
imports: import copy
  import os
  import shutil
  from collections import defaultdict
  from typing import IO, Dict, List, Optional, Tuple
  import numpy
  import torch
  from scipy.stats import beta, gamma
  from tqdm import tqdm
  from nemo.collections.asr.parts.preprocessing.perturb import AudioAugmentor
  from nemo.collections.asr.parts.preprocessing.segment import AudioSegment
  from nemo.collections.asr.parts.utils.manifest_utils import get_ctm_line, read_manifest, write_ctm, write_manifest, write_text
  from nemo.collections.asr.parts.utils.speaker_utils import labels_to_rttmfile
  from nemo.utils import logging
label_desc: Use image node_id 16 for calling a global function with example usage: add_silence_to_alignments(audio_manifest) and returns: audio_manifest