code: def _write_ply_header(
      f,
      *,
      verts: torch.Tensor,
      faces: Optional[torch.LongTensor],
      verts_normals: Optional[torch.Tensor],
      verts_colors: Optional[torch.Tensor],
      ascii: bool,
      colors_as_uint8: bool,
  ) -> None:
      """
      Internal implementation for writing header when saving to a .ply file.
  
      Args:
          f: File object to which the 3D data should be written.
          verts: FloatTensor of shape (V, 3) giving vertex coordinates.
          faces: LongTensor of shape (F, 3) giving faces.
          verts_normals: FloatTensor of shape (V, 3) giving vertex normals.
          verts_colors: FloatTensor of shape (V, 3) giving vertex colors.
          ascii: (bool) whether to use the ascii ply format.
          colors_as_uint8: Whether to save colors as numbers in the range
                      [0, 255] instead of float32.
      """
      assert not len(verts) or (verts.dim() == 2 and verts.size(1) == 3)
      assert (
          faces is None
          or not len(faces)
          or (faces.dim() == 2 and faces.size(1) == 3)
      )
      assert verts_normals is None or (
          verts_normals.dim() == 2 and verts_normals.size(1) == 3
      )
      assert verts_colors is None or (
          verts_colors.dim() == 2 and verts_colors.size(1) == 3
      )
  
      if ascii:
          f.write(b"ply\nformat ascii 1.0\n")
      elif sys.byteorder == "big":
          f.write(b"ply\nformat binary_big_endian 1.0\n")
      else:
          f.write(b"ply\nformat binary_little_endian 1.0\n")
      f.write(f"element vertex {verts.shape[0]}\n".encode("ascii"))
      f.write(b"property float x\n")
      f.write(b"property float y\n")
      f.write(b"property float z\n")
      if verts_normals is not None:
          f.write(b"property float nx\n")
          f.write(b"property float ny\n")
          f.write(b"property float nz\n")
      if verts_colors is not None:
          color_ply_type = b"uchar" if colors_as_uint8 else b"float"
          for color in (b"red", b"green", b"blue"):
              f.write(
                  b"property " + color_ply_type + b" " + color + b"\n"
              )
      if len(verts) and faces is not None:
          f.write(f"element face {faces.shape[0]}\n".encode("ascii"))
          f.write(b"property list uchar int vertex_index\n")
      f.write(b"end_header\n")
  
imports: import itertools
  import os
  import struct
  import sys
  import warnings
  from collections import namedtuple
  from dataclasses import asdict, dataclass
  from io import BytesIO, TextIOBase
  from typing import List, Optional, Tuple
  import numpy
  import torch
  from iopath.common.file_io import PathManager
  from pytorch3d.io.utils import _check_faces_indices, _make_tensor, _open_file, _read_image, PathOrStr
  from pytorch3d.renderer import TexturesUV, TexturesVertex
  from pytorch3d.structures import Meshes, Pointclouds
  from .pluggable_formats import endswith, MeshFormatInterpreter, PointcloudFormatInterpreter
label_desc: Use image node_id 17 for calling a global function with example usage: _write_ply_header(f) without return types