code: def _normalize_palette(im, palette, info):
      """
      Normalizes the palette for image.
        - Sets the palette to the incoming palette, if provided.
        - Ensures that there's a palette for L mode images
        - Optimizes the palette if necessary/desired.
  
      :param im: Image object
      :param palette: bytes object containing the source palette, or ....
      :param info: encoderinfo
      :returns: Image object
      """
      source_palette = None
      if palette:
          # a bytes palette
          if isinstance(palette, (bytes, bytearray, list)):
              source_palette = bytearray(palette[:768])
          if isinstance(palette, ImagePalette.ImagePalette):
              source_palette = bytearray(palette.palette)
  
      if im.mode == "P":
          if not source_palette:
              source_palette = im.im.getpalette("RGB")[:768]
      else:  # L-mode
          if not source_palette:
              source_palette = bytearray(i // 3 for i in range(768))
          im.palette = ImagePalette.ImagePalette(
              "RGB", palette=source_palette
          )
  
      if palette:
          used_palette_colors = []
          for i in range(0, len(source_palette), 3):
              source_color = tuple(source_palette[i : i + 3])
              try:
                  index = im.palette.colors[source_color]
              except KeyError:
                  index = None
              used_palette_colors.append(index)
          for i, index in enumerate(used_palette_colors):
              if index is None:
                  for j in range(len(used_palette_colors)):
                      if j not in used_palette_colors:
                          used_palette_colors[i] = j
                          break
          im = im.remap_palette(used_palette_colors)
      else:
          used_palette_colors = _get_optimize(im, info)
          if used_palette_colors is not None:
              return im.remap_palette(
                  used_palette_colors, source_palette
              )
  
      im.palette.palette = source_palette
      return im
  
imports: import itertools
  import math
  import os
  import subprocess
  from .None import Image, ImageChops, ImageFile, ImagePalette, ImageSequence
  from ._binary import i16le
  from ._binary import o8
  from ._binary import o16le
label_desc: Use image node_id 3 for calling a global function with example usage: _normalize_palette(im, palette, info) and returns: im, im