code: def _merge_OTL(font, model, master_fonts, axisTags):
      log.info("Merging OpenType Layout tables")
      merger = VariationMerger(model, axisTags, font)
  
      merger.mergeTables(font, master_fonts, ["GSUB", "GDEF", "GPOS"])
      store = merger.store_builder.finish()
      if not store:
          return
      try:
          GDEF = font["GDEF"].table
          assert GDEF.Version <= 0x00010002
      except KeyError:
          font["GDEF"] = newTable("GDEF")
          GDEFTable = font["GDEF"] = newTable("GDEF")
          GDEF = GDEFTable.table = ot.GDEF()
          GDEF.GlyphClassDef = None
          GDEF.AttachList = None
          GDEF.LigCaretList = None
          GDEF.MarkAttachClassDef = None
          GDEF.MarkGlyphSetsDef = None
  
      GDEF.Version = 0x00010003
      GDEF.VarStore = store
  
      # Optimize
      varidx_map = store.optimize()
      GDEF.remap_device_varidxes(varidx_map)
      if "GPOS" in font:
          font["GPOS"].table.remap_device_varidxes(varidx_map)
  
imports: from typing import List
  from fontTools.misc.vector import Vector
  from fontTools.misc.roundTools import noRound, otRound
  from fontTools.misc.fixedTools import floatToFixed
  from fontTools.misc.textTools import Tag, tostr
  from fontTools.ttLib import TTFont, newTable
  from fontTools.ttLib.tables._f_v_a_r import Axis, NamedInstance
  from fontTools.ttLib.tables._g_l_y_f import GlyphCoordinates, dropImpliedOnCurvePoints
  from fontTools.ttLib.tables.ttProgram import Program
  from fontTools.ttLib.tables.TupleVariation import TupleVariation
  from fontTools.ttLib.tables import otTables
  from fontTools.ttLib.tables.otBase import OTTableWriter
  from fontTools.varLib import builder, models, varStore
  from fontTools.varLib.merger import VariationMerger, COLRVariationMerger
  from fontTools.varLib.mvar import MVAR_ENTRIES
  from fontTools.varLib.iup import iup_delta_optimize
  from fontTools.varLib.featureVars import addFeatureVariations
  from fontTools.designspaceLib import DesignSpaceDocument, InstanceDescriptor
  from fontTools.designspaceLib.split import splitInterpolable, splitVariableFonts
  from fontTools.varLib.stat import buildVFStatTable
  from fontTools.colorLib.builder import buildColrV1
  from fontTools.colorLib.unbuilder import unbuildColrV1
  from functools import partial
  from collections import OrderedDict, defaultdict, namedtuple
  import os.path
  import logging
  from copy import deepcopy
  from pprint import pformat
  from re import fullmatch
  from .errors import VarLibError, VarLibValidationError
label_desc: Use image node_id 13 for calling a global function with example usage: _merge_OTL(font, model, master_fonts, axisTags) without return types