code: def export_to_ply(mesh, output_ply_path: str = None):
      """
      Write a PLY file for a mesh.
      """
      if output_ply_path is None:
          output_ply_path = tempfile.NamedTemporaryFile(
              suffix=".ply"
          ).name
  
      coords = mesh.verts.detach().cpu().numpy()
      faces = mesh.faces.cpu().numpy()
      rgb = np.stack(
          [
              mesh.vertex_channels[x].detach().cpu().numpy()
              for x in "RGB"
          ],
          axis=1,
      )
  
      with buffered_writer(open(output_ply_path, "wb")) as f:
          f.write(b"ply\n")
          f.write(b"format binary_little_endian 1.0\n")
          f.write(bytes(f"element vertex {len(coords)}\n", "ascii"))
          f.write(b"property float x\n")
          f.write(b"property float y\n")
          f.write(b"property float z\n")
          if rgb is not None:
              f.write(b"property uchar red\n")
              f.write(b"property uchar green\n")
              f.write(b"property uchar blue\n")
          if faces is not None:
              f.write(bytes(f"element face {len(faces)}\n", "ascii"))
              f.write(b"property list uchar int vertex_index\n")
          f.write(b"end_header\n")
  
          if rgb is not None:
              rgb = (rgb * 255.499).round().astype(int)
              vertices = [
                  (*coord, *rgb)
                  for coord, rgb in zip(
                      coords.tolist(),
                      rgb.tolist(),
                  )
              ]
              format = struct.Struct("<3f3B")
              for item in vertices:
                  f.write(format.pack(*item))
          else:
              format = struct.Struct("<3f")
              for vertex in coords.tolist():
                  f.write(format.pack(*vertex))
  
          if faces is not None:
              format = struct.Struct("<B3I")
              for tri in faces.tolist():
                  f.write(format.pack(len(tri), *tri))
  
      return output_ply_path
  
file_path: diffusers/src/diffusers/utils/export_utils.py
imports: import io
  import random
  import struct
  import tempfile
  from contextlib import contextmanager
  from typing import List, Union
  import numpy
  import PIL.Image
  import PIL.ImageOps
  from .import_utils import BACKENDS_MAPPING, is_opencv_available
  from .logging import get_logger
label_desc: Use image node_id 3 for calling a global function with example usage: export_to_ply(mesh, output_ply_path) and returns: output_ply_path