code: def toXML(self, writer, ttFont):
      attrs = dict(coverage=self.coverage, format=self.format)
      if self.apple:
          if self.tupleIndex is None:
              log.warning("'tupleIndex' is None; default to 0")
              attrs["tupleIndex"] = 0
          else:
              attrs["tupleIndex"] = self.tupleIndex
      writer.begintag("kernsubtable", **attrs)
      writer.newline()
      items = sorted(self.kernTable.items())
      for (left, right), value in items:
          writer.simpletag(
              "pair", [("l", left), ("r", right), ("v", value)]
          )
          writer.newline()
      writer.endtag("kernsubtable")
      writer.newline()
  
imports: from fontTools.ttLib import getSearchRange
  from fontTools.misc.textTools import safeEval, readHex
  from fontTools.misc.fixedTools import fixedToFloat, floatToFixed
  from .None import DefaultTable
  import struct
  import sys
  import array
  import logging
label_desc: Use image node_id 4 for calling the KernTable_format_0 obj's underlying member method code with example usage: obj.toXML(writer, ttFont) without return types