code: def writeTTCHeader(file, numFonts):
      self = SimpleNamespace()
      self.TTCTag = "ttcf"
      self.Version = 0x00010000
      self.numFonts = numFonts
      file.seek(0)
      file.write(sstruct.pack(ttcHeaderFormat, self))
      offset = file.tell()
      file.write(
          struct.pack(">%dL" % self.numFonts, *([0] * self.numFonts))
      )
      return offset
  
imports: from io import BytesIO
  from types import SimpleNamespace
  from fontTools.misc.textTools import Tag
  from fontTools.misc import sstruct
  from fontTools.ttLib import TTLibError, TTLibFileIsCollectionError
  import struct
  from collections import OrderedDict
  import logging
label_desc: Use image node_id 4 for calling a global function with example usage: writeTTCHeader(file, numFonts) and returns: offset