code: def merge_video_and_audio(
      video_path: str,
      audio_path: Optional[str],
      output_path: str,
  ) -> None:
      ffmpeg_command = []
  
      if audio_path:
          ffmpeg_command = [
              "-y",
              "-i",
              video_path,
              "-i",
              audio_path,
              "-vf",
              "format=pix_fmts=yuv420p",
              "-c:v",
              "libx264",
              "-c:a",
              "copy",
              "-bsf:a",
              "aac_adtstoasc",
              "-preset",
              "ultrafast",
              output_path,
          ]
      else:
          ffmpeg_command = [
              "-y",
              "-i",
              video_path,
              "-vf",
              "format=pix_fmts=yuv420p",
              "-c:v",
              "libx264",
              "-c:a",
              "copy",
              "-bsf:a",
              "aac_adtstoasc",
              "-preset",
              "ultrafast",
              output_path,
          ]
  
      execute_vidgear_command(output_path, ffmpeg_command)
  
imports: import math
  import os
  import shutil
  import tempfile
  from typing import Any, Dict, List, Optional
  import ffmpeg
  import numpy
  from augly.audio import utils
  from augly.utils import pathmgr, SILENT_AUDIO_PATH
  from augly.utils.ffmpeg import FFMPEG_PATH, FFPROBE_PATH
  from vidgear.gears import WriteGear
label_desc: Use image node_id 10 for calling a global function with example usage: merge_video_and_audio(video_path, audio_path, output_path) without return types