code: def validate_header(self, data, offset):
      magic = bytes(data[offset : offset + 4])
      if magic == b"GGUF":
          raise ValueError("File is already in GGUF format.")
      if magic == b"lmgg":
          self.file_format = GGMLFormat.GGML
          self.format_version = 1
          return 4
      version = struct.unpack("<I", data[offset + 4 : offset + 8])[0]
      if magic == b"fmgg":
          if version != 1:
              raise ValueError(
                  f"Cannot handle unexpected GGMF file version {version}"
              )
          self.file_format = GGMLFormat.GGMF
          self.format_version = version
          return 8
      if magic == b"tjgg":
          if version < 1 or version > 3:
              raise ValueError(
                  f"Cannot handle unexpected GGJT file version {version}"
              )
          self.file_format = GGMLFormat.GGJT
          self.format_version = version
          return 8
      raise ValueError(
          f"Unexpected file magic {magic!r}! This doesn't look like a GGML format file."
      )
  
imports: from __future__ import annotations
  import argparse
  import struct
  import sys
  from enum import IntEnum
  from pathlib import Path
  import numpy
  import os
  import gguf
label_desc: Use image node_id 2 for calling the GGMLModel obj's underlying member method code with example usage: obj.validate_header(data, offset) and returns: int, int, int